About NICRA in CMFRl

(1)

«

U'AH

Cc0j(.CB OTOl21^(.f3 (2(30)^ a )G 0 1 n il6 m (TUDOaJCDo (QSOOIcQ) ce>0(3niiled) COdfUnSim cB)'D6n^(TVM)

(Jl.eoil. cncnid 1603. qqostooa^s^ ®cnoc5ana)“ o il .s.. o<a>o^V 682018, ocd^ogo. gooRD]^

CMFRI

(2)

nuoO oeAflJii nj)<s>nucn â J ô I â JD ^s I

< e > }e i}m n u D 3 t o ia a n lia n a im Q a n u j< s > jn & n - 2 0 1 5

Published by

D r. A. G o p a la k rish n a n D ire cto r

IC A R - C e n t r a l M arin e Fish e rie s R esearch Institute (In d ia n C o u n c il o f A g ric u ltu ra l R e se a rch )

Ern aku lam North P .O ., P. B. N o. 16 03 C o c h in - 682 018. Kerala. India

Edited by

Dr. Shinoj Subramannian Dr. P.A. V ik a s S hri.F.P ushparaj A n je lo K V K Ernakulam of C M F R I

Central Marine F ish e rie s R e se a rch Institute

( In d ia n C o u n c il o f A g ric u ltu ra l R e s e a rc h )

P o s t B o x N o .1603, E rn a k u la m N o rth P.O., K o ch i - 6 8 2 018, India

(3)

cA)o(Oo(ic&(a)j ojldfccrucD ojoIojosI

cfiboejoojcruLDO (araaBlszlcua) a«sn;^da>^<^1-20i5

ISBN : 978^3-82263-09-8

C<iJcroocoda>aS

cojuo. ofi).ccno<iJoejc&^<^6mnRi

CU)CD)0<& S^

CS(fe£.n3 Oiasc^j^ COCSCUnadGm CrODOnJCDo

(BGud^QQ) d&o^nad'ltfe 05cs0Jriad6iT) (feTDffn6cru1co6

mau^ 1603, côewosîô ojI.sb.

Qd&o^l - 682018, QtftiCO^o, ^OU)^

vwwv.cmfri.org. in

^ 0 2o1(o3: director@cmfri.org.in eoDasn^: +91 0 4 8 4 2394867 oDddao: +91 0 4 8 4 239 49 0 9

^[lUOCDGm n^dlCSmO^ CTO^L^Caffm^n^, ajid&ocro rul.n^., rJJn3drJ(Q0^ (^Ot^QOJO, ag]aD. Ed.(2015) CrOo0of§(feC?i)J

ojldfccrocn rJCOlrJOSl : d0DO&JOaJCniDO C5ra(?i)1^®IOJm I2(;yr0^(fe^nad1-2015, Cro1.a^o.n^aD.G5T&)^.0n^. - cmlctfe Cf^CroltlU'ld&CDGrDo

cncTUiS 4, QtfticnB crotajLf^ Qorru^ a:icsojnadem croDOnJCDo, ©d&o^l, 97 Qnj^.

nJJCrO(JJ)te3(m^1(EJ^ ^rJQCOJOCQl^1(Ql(e€)JCrO g)63gS(e€)(gtaO i2jl£.(^3)5HT3CS^O,

CnJmJOCJUtft.0n§ C5ramjt2C?i)1cSQ2J06)S rj^cn0ooj1n3d(fe0'lce€)orrt rJ0s1^.

o^QtftiOrJCiDo : 06)&JC6TUo1 Sc Qajuotfe^jQiacsn^riadn^ Qcroog^

I S B N 9 7 8 - 9 3 - 8 2 2 6 3 - 0 9 - 8

Qiiissmo -. ocrong" t.fiDoa3mj1cro C^cnl, ocfoo^l - 682 ois

9 7 8 9 3 8 2 ' 2 6 3 0 9 8 >

(4)

PREFACE

Aquaculture is one o f the fastest growing food production system in the world.

Kerala State is bestowed with large num ber o f potential w ater bodies suitable for aquaculture. There are num ber of graduates in aquaculture passing out from both technical and conventional colleges and universities who divert their expertise to non

aquaculture fields due to lack o f sufficient em ploym ent opportunities in this sector. On the o ther hand, there is am ple scope fo r authorized consultancy services/service providers to aquaculture farm ers and (or) scope for scientific aquaculture ventures. Aquaculture is a vast area which possess different aspects such as pond preparation, intensive farm ing m odels, seed sourcing and stocking, value added product developm ent, high density farm ing, ornam ental fish breeding & rearing, w ater quality analysis, branding, marketing, etc. This ED P w as conducted with the objective o f exposing selected group o f young professionals to self-em ploym ent avenues in Aquaculture. Fourteen select youth between age group o f 18 and 35 participated, m ajority o f them are highly educated professionals, i.e., B.Techs, MBAs and so on. Th is is an indication of growing interest o f youth towards agriculture. There is a ray of hope that Kerala agriculture has a bright future in the hands o f yo ung er generations which can be a trend setter for other states in the country. I wish all the very best and success for the all participants fo r their future endeavors.

W ith B e st W ishes,

(A. Gopalakrishnan) Director

(5)

(6)

About NICRA in CMFRl

Climate change is one of the major challenge for countries like India which has a population strength of over 1.2 billion people and most of the people depend on agriculture for their livelihood.

Govt, of India has accorded high priority on research and development to cope with climate change in agricultural sector. Indian Council of Agricultural Research (ICAR) has launched a major national scheme "National Innovations on Climate Resilient Agriculture (NICRA)" during l l ' ” plan with an outlay of 350 crores. The major focus of the programme is to

• Enhance the resilience of Indian agriculture covering crops, livestock and fisheries to climatic variability and climate change through development and application of improved production and risk management technologies

• Demonstrate site specific technology packages on farmers fields for adapting to current climate risks

• Enhance the capacity building of scientists and other stakeholders in climate resilient agricultural research and its application.

The unique feature of the project is the multidisciplinary approach covering all commodities like crops, horticulture, livestock and fisheries besides natural resource management and socio

economic research. Another important feature is the project is the technology demonstration component which aims at on-farm participatory demonstration of available climate coping technologies in select districts.

Most of the Pokkali fields in Kerala are kept fallow due to less profitability. KVK with funding support from NICRA have tried to demonstrate that pokkali farming can be made profitable by integrating with fish farming in cages. For this, Pokkali farm ers from Pizhala, Ezhikkara and Kadam akkudy Nedungad, Kumbalangi regions were selected. Fish seeds of Pearl spot, Mullet, Pompano (Trachinotus blochii) species have been introduced in the cages during November after the pokkali rice harvest and harvested in March of next year.

The demonstrated tech n o lo g yo fcag ecu ltu reo ffin fish in Pokkali fields resulted in additional net income o f 0,80 lakhs/ha resulting a total net income of 1.3 lakhs/ha. The net income in case of paddy cultivation alone would be INR 0.15 lakhs/ha, whereas paddy and shrimp together give income of only 0.50 lakhs/ha. Formulated pellet feed for Pearl spot, Etroplus surratensis larvae and juveniles developed under CADALMIN^" brand in the trade name - Pearl Plus for feeding pearl spot

during Pokkali integrated farming.

This entrepreneurship training for young fish farmers is arranged as part of CMFRI-NICRA KVK initiative of demonstrating viable clim ate resilient technologies in farmers' field and attract youngsters to enter in the field of agriculture.

RU. Zacharia PI NICRA Project, CMFRI

(7)

(8)

Acknowledgement

W e th a n k Dr. A .G o p a la k rish a n a n , Director, IC A R -C e n tral M arin e Fish eries Research In stitu te , Kochi and Dr. RU. Z ach a ria , Principal In v e stig a to r of N IC R A Project san ctio n in g th is e n terp ren eu rsh ip d eve lo p e m en t p ro g ram m e on clim ate resilient aq u acu ltu re and also to extend all n e ce ssa ry facilitie s o f the in stitu te. T h a n ks are due to Dr. P V ijayag o p al, H ead, M BT D ivision of C M FR I fo r sparing the nutritio n lab o f th e d ivisio n to co nd uct han d s on train in g on feed p ro d u ctio n . W e th a n k all the fa c u lty m em b ers, su b je ct exp erts, p ro g ressive farm e rs and e n tre p ren eu rs a sso ciate d w ith th is p ro g ram m e. O rg an isatio n s such as M arin e Pro d ucts Exp o rt D evelo p m en t A u th o rity (M P ED A ) Kochi, C en tre fo r Fish D iseases D iag n o sis and M an ag em en t, C o ch in U n iversity o f S cien ce and Technology, (CU SA T) Kochi, Fish Farm ers D evelo p m en t A u th o rity (FFD A ), Ern aku lam and M atsyafed N et facto ry, Kochi are also a ckn o w led g e d fo r exten d in g v a rio u s facilities.

Team KVK

(9)

(10)

A q u a cu ltu re nutritio n in vo lves the science and art o f feed in g a q u atic a n im als in co nfined e n viro n m e n t. M ost o f the a q u atic o rg an ism s cultured fo rfo o d or fo r o rn am e n tal p urposes by h o b b yists at so m e stag e requires e xo g e n o u s feed in g . Th is in put is given in the form of feed p ro d u cts w h ich are produced using several te ch n iq u e s and tech n o lo g ie s.

B usiness o p p o rtu n itie s in th is secto r are dual in nature. O ne is trad in g m o stly by im port.

N ext is in d ig en o u s so urcing and trad e or in d ig en o u s p roduction

Present Status

At present fee d s fo r grow out o f m ost aq u atic a n im als cultured in Ind ia is su p p o rted by a strong in d ig en o u s p ro d uctio n base. Feeds fo r fre sh w a ter fish cu ltu re and shrim p cu lture are p ro d uced in 26 m ills w ith an in stalled pro d uctio n ca p acity of 2.88 M illion M etric Tonnes (M M T) per a n n u m . It is also reported by the A m e rican So yb ean A sso ciatio n that th e se feed m ills produced and m arketed 1.25 M M T feed in 2013 in d icatin g a cap acity u tilizatio n o f 4 3 .4 % . T h is m eans th at there is a lre a d y an in stalled cap acity availab le to e n h an ce p ro d uctio n. Venturing into this seg m e n t at p resent d o es not m ake sense at present.

B him avaram in A n d h ra Pradesh can be called the a q u acu ltu re capital o f India.

Ko lath u r in C h en n ai, Tamil Nadu is the place w h ere o rn am en tal fish p ro d ucts and services are co n ce n tra ted . All o th er m etros w ith a g row in g m arket are catered from C h en n ai.

W ith aq u acu ltu re grow in g in d o ub le d ig its in m ost o f the A sian co u n tries for the past d ecade, fish p ro d uctio n is the faste st grow in g fo o d pro d ucing secto r in the w o rld . U n d e rstan d in g th is and then looking into w h ere th ere are o p p o rtu n ities o f en tre p ren eu rsh ip , in itia lly it could be im p o rt and tra d e o f p ro d ucts w h ich are not m an u factu red in In d ia. Th is is h ap pening in a seg m e n t of a q u atic fee d s called m icro feeds w h ich are not m an u factu red in Ind ia. Im p o rt su b stitu tio n is th e o p p o rtu n ity here.

M icro fee d s are fee d s used to feed new born fish es. M ost fish w ith y o lk have a n o n feed in g stag e a fte r w h ich th e y start feed ing on m icro a lg ae in th e size range of less than 10 m icrons. Then as th e fish grow th p ro g resses, th eir m outh size in crea ses and feed in g p referen ces ch an ge a cco rd in g to w h ich , fee d s o f d ifferen t b u o yan cie s and sizes ranging from less th an 10 m icrons to 1.5 mm fall in th is category.

All th e se fish feed pro d uctio n tech n o lo g ie s are capital in ten sive. For e.g., a sh rim p feed p ro d uctio n p la n tw h ic h is a s te a m pelletizatio n pro cess to d a y req uires an in ve stm e n t of 1 crore. Extru d e rs w h ich p ro d u ce flo ating feed s fo r cu ltu re o p era tio n s require an in vestm en t o f 5crores fo r m a ch in e ry alo n e b ecau se the m a ch in e ry has to be im p o rted . T w in -screw e xtru d ers are m ore co stly than th is. W ith all a d d -o n s it to u ch es 10 crores.

Sm all and m edium e n terp rise s (S M E) in this seg m e n t are a p o ssib ility w ith m ach ines o f lo w er capacity. H ow ever, th is requires research in so urcing eq u ip m en t m ainly

(13)

fro m fo o d secto r and p harm a sector. Th is is b ecau se the m any o f the p ro cesses are co m m o n acro ss th e se secto rs.

M arket research w h ich is v e ry im p o rta n tw h e n w e are p lanning in d ig en o u s pro d uctio n and sale such p ro d u cts. In one o f our su rve ys w e have fo u n d th at C h en n ai m arket co n su m es 2500 to n n e s of m icro fee d s a n n u a lly out of w h ich 50% is m et th ro u g h im port.

O p p o rtu n itie s in feed secto r

1. Im p o rt and trad e o f m icro feed p ro d u cts th ro u g h a o n e -sto p -sh o p fo r a q u acu ltu re

p ro d u cts w h ich is yet to begin in a state like Kerala.

2. E stab lish m e n t o f o n -farm feed m aking u nits fo r sh rim p cu lture fo r w h ich initial in ve stm e n t is low.

3. M icro feed p ro d uctio n w ith in d ig en o u s m ach in es like the one fu n ctio n al in the C M FRI.

T h e se a sp e cts w ill be d iscu ssed in detail in a classro o m sessio n w h ich w ill be fo llo w ed by a d em o n stratio n o f m icro feed p ro d uctio n in a tw in -screw extruder.

B ran d ed Feed In d igen ou s Feed

O n e stop A q u acu ltu re shop Sm all Scale Feed M ill U nit

(14)

SHRIMP DISEASES AND DISEASE MANAGEMENT

Dr. I .S. Bright Singh

C oord inato r, C en tre fo r Fish D isease D iag n o sis and M an ag em en t Cochin U n iversity o f Scien ce and Technology,

Lake Side C am p u s, Fine A rts A ven u e, C o ch in - 682016 b sin g h @ m d 3 .v sn l.n e t.in ; W eb: cfddm .org

Pho n e/Fax: 0 4 8 4 - 2381120

Introduction

In recent y e a rs, th ere has taken place an e xp o n en tial grow th o f sh rim p farm in g in coastal India b ecause of the lu crative in com e earned by early en tran ts. H ow ever, the exp ansio n o f the culture w a s not planned and m an y vital scien tific p rin cip les in site selectio n and m an a g em en t w ere igno red.

The d efe ctive w a te r in take and d rain ag e system s created a e u tro p h ic co n d itio n of m any w a te r resources. A s a cu m u lative effect shrim p cu ltu re ran into in cre a sin g ly co m p lex p ro b lem s like partial or m ass m o rtalities due to e ith er d iseases or en viro n m en tal im p airm en t. U ltim a tely the sud d en o u tb reak o f w h ite spo t d ise ase in late 1994, th reaten ed even th e v e ry e xisten ce o f th e in du stry.

Th is a rticle d eals w ith the im p o rta n t diseases o b served m ain ly in the cu ltu re p o nd s of coastal zo n es o f India in g en eral.

Infectious Diseases

In fe ctio u s d ise ase s are th e o n es w ith d efinite a etio lo g ic a g en t and can be tran sm itted both v e rtic a lly and ho rizo ntally. V iru se s, bacteria, fu n g i and p ro to zo an s cause th ese diseases.

Viruses

It is believed th at illegal im p o rt of the in fected b ro o d sto ck and seed to m eet the seed sh o rtag e during 1994 resulted in the in tro d u ctio n of viral in fe ctio n s in Ind ia.

M o no d o n B acu lo viru s (M B V ) and System ic Ecto derm al and M eso d erm al B acu lo viru s (S EM B V ) now called W h ite Spot D isease

V iru s (W SD V ) and H e p ato p an cre atic Parvo - like V iru s (H PV ) have been the m ost im p o rta n t viru se s recorded in Ind ia besides the not so co n firm ed p resen ce o f In fectio u s H ypo derm al and H aem ato p o ietic N ecrosis V iru s (IH H N V ) and Yellow Head V iru s (YH V) (Fleg el, 1997)

Monodon Baculovirus (MBV) Disease

M BV in fects all life stag es o f P m o n o d o n and P in d icu s and is tra n sm itte d v e rtic a lly from the b ro o d -sto ck to th e eggs and h o rizo n tally from one pond to a n o th e r th ro u g h the v irio n s and o cclu sio n bodies. Bro o d sto ck m ay be the carriers, th o u g h th e y do not e xh ib it a n y p atho lo g ical signs as long as the e n viro n m en tal co n d itio n s are favo u rab le.

Seed pro d uctio n in h atch eries is g reatly affected by M BV in fectio n . M BV can be id en tified by the p resence o f round occlu sion bod ies in the n u cleu s of the h ep ato p an creatic cells. M oribu nd shrim p e xh ib it d isco lo ratio n o f the body. U n d er ideal rearing co n d itio n s the v iru s do not cause a n y a b n o rm al m o rtality o f larvae and post larvae. The m ajo r clinical sig n s are reduced feed in g and grow th rates and an in crease in gill and su rface fo uling . S e verely in fected p raw n s m ay d isp la y a w h ite h ep ato p an creas and m idgut.

M BV fo rm s large, ro u g h ly sp h erical, o esino philic, p o lyhed ral o cclu sio n b o d ie s(O B 's)w ith in the nuclei of h ep ato p an creatic cells. OB's m ay o ccu r sin g u la rly or in m ultip les. Early in fectio n m ay be d etected by th e p resence o f h yp ertro p h ie d nuclei w ith m arginated ch ro m atin and d isp laced nu cleo lu s. In heavy

(15)

in fe ctio n s the a n te rio r m idg u t ep ith eliu m m a y a ls o be in fected (Lightner, 1983, Ligh tn er et al., 1983 and Lightner, 1988).

D efin itive d ia g n o sis is based on the histo lo g ical d em o n stratio n o f o e sin o p h ilic O B 'sw ith in the nuclei o f h ep ato p an creo cytes.

O B's m ay also be detected in fresh squash p rep aratio n s o f the h ep ato p an creas stained w ith 0 .5 % a q u eo u s m alach ite green. D N A p ro b es fo r M BV have been d evelo p ed in several co u n tries and are the m ost reliable m ethod o f d etectin g M BV in fectio n . A co m m ercial d iag n o stic probe is availab le fro m D iag X o tics Co. Ltd., W ilto n CT and p rim ers fo r PCR d ia g n o sis have been p u blish ed by C hang et al.(1 9 93 ). A new m ethod o f M BV reaction PCR has been d evelo p ed (Belcher, 1997).. T h is d etectio n a ssa y p ro vides in fo rm atio n a b o u t each M BV iso late at D N A level and the in fo rm atio n can be used to d istin g u ish iso lates and allo w g e n e tica lly sim ilar iso lates to be gro u ped acco rd in g to v iru le n c e or g eo g rap h ic origin.

O tta et al. (2003) co uld d etect M BV in 54% of post-larval sam p les by PCR

M BV is tra n sm itte d by in g estio n o f free v iru s and O B's and by can n ib alism (P ayn ter et al., 1992) and v e rtic a lly from brood sto ck to o ffsp ring (B o n am i etal., 1986). W ater b orne tran sm issio n has been d em o n strated su g g estin g its cap ab ility to rem ain a live in th e e n viro n m e n t o f the p o lyhed ral occlu sion bo d ies. (N ativid ad and Lightner., 1992 and Fed erici, 1986).

M BV is co n tro lled in h a tch e ry by avo id in g co n tam in atio n and by strict d isin fectio n reg im es. In fected a n im als sho uld be e rad icated and rem o ved from th e facility (Lightner, 1988). All e q u ip m en t ta n ks should be d isin fected ro u tin ely betw een batches o f larvae and the eq u ip m en t used in the sp aw n in g area sho uld be seg reg ated from th e hatchery. Eggs sho uld be sep arated fro m the sp a w n e r fae ce s in w h ich M BV OB's m ay be present. W ash in g eggs w ith clean

seaw ater, io d o p h o re (20 ppm fo r 30 seco nd s) and fo rm alin lOOppm fo r 30 seco n d s and a su b se q u e n t w ash o f naupliai w ith 100 ppm fo rm alin fo r 30 seco n d s and 50 ppm io d o p h o re has been reco m m en d ed (Chen et al., 1992) have been reco m m en d ed .

U n d er farm in g co n d itio n s, severe M BV in fectio n leads to stunted g ro w th , a situation th a t m akes the w h o le g ro w o u t phase no n viable.

Sto ckin g p o nd s w ith M BV free post larvae is th e o n ly w a y out to escap e from th is viru s u n d e r the present situatio n .

W hite Spot Syndrome Virus

W h ite Sp o t Syn d ro m e V iru s (W SSV ) now called W h ite Sp o t D isease V iru s (W SD V ) is resp o n sib le fo r severe in fectio n and m ass m o rta lities in P m o n o d o n and P in d icu s and cau se the m ost v iru le n t W h ite spot d ise ase in th e late 1994 in Ind ia. The viru s is know n as h yp o d erm al h em ato p o ietic n ecro sis b acu lo viru s (IH H N V ; H uang et al., 1994) in C hina, ro d -sh ap ed n uclear v iru s o f P.japanicus (R V -Pj; In o u ye et al.,

1994) in Jap an , C hina and Korea; System ic Ecto d erm al and M eso d erm al B acu lo viru s (S EM B V ; W o n g tee rasu p aya et al., 1995 and W n g te e ra su p aya , 1996) in Th a ilan d ; W hite Sp o t B acu lo viru s (W SSV ; W ang et al., 1995, 1997) in Taiwan and S EM B V in Bangladesh (A h m ed , 1996).

All viru se s in th is grou p are reported to be v e ry sim ilar in m o rp h o lo g y and rep licate in th e nuclei o f in fected cells. Ligh tn er et al., (1997) co n sid er them to be sim ilar, if not th e sam e viru s. W h ite Sp o t Syn d ro m e V irus is not a b acu lo viru s (V olkm an et al., 1995) so it is p referab le to refer to it as W hite Sp o t Syn d ro m e V iru s or W SSV. Recently it is renam ed as W h ite Sp o t D isease V irus (W SD V ).

T h e m ost co m m o n sym pto m of this in fectio n is a p p e ara n ce of w h ite spo ts in th e e xo skeleto n . W h ite sp o ts are m ore

(16)

co n sp icu o u s in the shell o f P.m onodon than in R in d icu s. It is a syste m ic in tra n u clea r viru s affe ctin g gills, h ep ato p an creas n erve cord, an ten n al gland, cu ticu la r epith eliu m and lym p ho id organ and fo r th at m atter all organs and tissu e s of ecto d erm al and m eso d erm al o rig in . M ost o f the affected shrim p exh ib its ab n o rm al sw im m in g behaviour, loss of a p p etite, leth arg y and fin a lly m ass m o rtality o ccu rs u su a lly w ith in a period of 3-7 days.

The in fected prawn m ay d isp la y p ink to red d isco lo u ratio n of th e b o d y su rface and ap p e n d ag e s.

The in fected cells are ch aracterized by h yp ertro p h ied nuclei w ith m arginated ch ro m atin and o e sin o p h ilic to baso p hilic in tra n u clea r in clu sio n s. D iag n o sis o f w h ite spo t syn d ro m e d ep e n d s m ain ly on the d em o n stratio n o f o e sin o p h ilic to baso p hilic in clu sio n bod ies in stained fresh sq u ash es or im p ressio n sm e ars o f ecto d erm al and m eso d erm al tissu es. F eu lg en -p o sitive intra n uclear in clu sio n b o d ies m ay be identified in cu ticu la r epith elial cells and co n n ective tissu e cells. A s a rapid field test fo r W S S V the gills and ep ith eliu m u n d e r the carap ace are excised stained w ith h aem o to xylin and eosin, m o u nted and then vie w e d as squash p reparatio n (Flegel and Sriu ria ira tan a, 1993).

The in fectio n m ay fu rth e r be co n firm ed by electron m icroscopy.

D iag n o stic D N A p ro b es have been d evelo p ed (W o n g teerasu p aya e ta l., 1 9 9 6 )a n d p ublished p rim ers are availab le fo r PCR a ssa ys (Kim ura et al., 1996, Lo et al., 1996a and b). In India, tw o co m m ercial PC R kits have been released by M /s. M an g alo re G enei Pvt. Ltd., Bangalore, M /s. M an g alo re Biotech, M an galore.

Recent e xp e rim en ts and su rveys using d iag n o stic PCR have show n that a p p ro x im a te ly fo rty a rth ro p o d s a c t as carriers o f W SSV. W ithin the cu ltu re system W S S V is tran sm itted by can n ib alizatio n o f m oribund p raw n s and carcasses or via co n tam in ated w a te r (C hang et al., 1996). C ru stacean

carriers th at en ter prawn p o nd s m ay tran sm it the v iru s w h en th e y die and are eaten by p raw n s and m ay m e ch a n ica lly tra n sm it the v iru s betw een ponds by releasing captu red p raw n s from o ver n eig h b o u rin g ponds.

Tran sm issio n o f the v iru s th ro ug h post larvae is u n e q u ivo cally e stab lish e d . H ow ever, the m ode o f tran sm issio n o f th e v iru s from the parent to nauplii is a co n tro versial issue.

O ne scho ol o f th o u g h t is th at the viru s g ets tran sm itted th ro u g h in fected O ogonia (Kou et al., 1997) and (M ohan et al., 1997).

M ean w h ile th e o th er scho ol says th at the v iru s kills the in fected m ature egg cells before m aturatio n (Lo et al., 1997) and a d irect tra n sm issio n th ro u g h the in fected e g g s is a rem o te possibility.

Literatu re says th at the v iru s can rem ain v ia b le in sea w a te r fo r 4 to 7 d ays. But our exp e rien ce is th a t the v irio n s in sea w a te r can rem ain v ia b le fo r o n ly 3 d ays (u n p u b lish ed ).

W S S V is being co n tro lled by the use of closed and sem iclo sed system s in vo lving the p re tre atm e n t o f w a te r w ith fo rm alin or ch lo rin e (10 ppm e ffective co n ce n tra tio n ) and sto rag e o f a n y w a t e r t o be exch an g ed for m ore than three d ays fo r so lar d isin fectio n . It is likely that, effectiven ess o f treatm en t w o u ld dep end upon the q u a n tity o f viru s p resent in the system . Elim in atio n o f fresh feed from the diet, exclusio n o f potential carriers from praw n cu ltu re p o nd s and PCR screening o f post larvae prior to stocking and im p lem en tatio n o f closed system w ith to p ing up o f w ate r or closed recirculatio n system co u pled w ith b io rem ed iatio n are also reco m m en d ed as m an a g em en t m easu res.

Hepatopancreatic Parvo-like Virus

Th is is a sin g le stran d ed D N A v iru s o b served in A sia in clu d in g In d ia. The v iru s has been found th ro ug h o ut the w o rld and has p otential to in fect d ifferen t shrim p species. Mid ju v e n ile sh rim p s are the m ain stag es affected by th is viru s. G ro ss signs

(17)

o f th is d isease are n ecro sis and a tro p h y of h e p to p an creas low shrim p g ro w th , anorexia and an in crease o f ep ico m m en sal o rg an ism s on b o d y su rface and gill, se co n d a ry bacterial and fungal in fectio n . M o rta lity has been o b served u n d e r stressful co n d itio n s a tta in in g 100% w ith in 4-8 w e e ks. (G uzm an, 2000). A D N A d ia g n o stic probe has been d evelo p ed by M ari et al., (1995) and is co m m e rcia lly availab le from D iag X o tics of W ilto n , C o n n e cticu t USA. B esid es thro ugh d ia g n o stic PC R also it w o u ld be p o ssib le to screen post larvae fo r the p resence o f HPV and also sh rim p feces fo r n o n -d estru ctive screen in g of brood stock.

Infectious Hypodermal and Haematpoietic Necrosis Virus (IHHNV) Disease

IH H N V is a pro b able p arvo viru s th at has been fo u n d in the U nited States, Sou th A m erica, Sou th East A sia and Israel. The viru s in fects cu ticu la r h yp o d erm is, blood cells, lym phoid organ and co n n e ctive tissu es. It m ay be p resent in larval stag e s as a latent in fectio n . T h e p resen ce o f IH H N V is su sp ected in Ind ia, but no evid en ce has been o b tain ed so far.

It is d istribu ted w id e ly in Penaeid cu lture facilitie s in Asia and A m erica and is believed to be en zo o tic in w ild rese rvo ir hosts such as P m o n o d o n (B ro ck and Lightner, 1990, Lig h tn er et al., 1983a and K alag ayan , et al., 1991).

P in d icu s m ay be in fected w ith the v iru s but do not sh o w sig n s o f th e d isease. Bo nam ie, et al., (1990) d escrib ed the IH H N V D N A ss g en o m e and fo rm s th e basis fo r classificatio n o f the v iru s as a pro b able p arvo viru s.

T h e clinical sig n s o f the d ise ase in clu de a n o rexia , le th arg y and erratic sw im m in g . Early larvae and post larvae, w h ich have been v e rtic a lly in fected , do not b ecom e diseased until th e y are o ld e r enough to be w ith in the size range o f 0 .0 5 to I g (Lightner, et al., 1983).

In fe cted p raw n s have been o b served to rise to the w ate r su rface , rem ain m o tio n le ss for a few m o m en ts then role o ver and sin k to

th e botto m . Th is b eh avio u r m ay be repeated until m o rta lity o ccu rs w h ich m ay be 90% . P m o n o d o n m ay a p p e a r clin ica lly norm al w h en h e a vily in fected w ith IH H N V (Fleg al,

1997).

IH H N V m ay be d iag n o ise d by the d em o n stra tio n o f C o w d ry Type A in clu sion b o d ie su sin g routine h isto chem ica I tech n iq u es fo r light and electro n m icroscop y. IH H N V sp e cific g en e p robes have been d evelo p ed fo r use in situ and dot blot h yb ridizatio n (Lightner, et al., 1992; M ari et al., 1993).

W ith th e se p ro b es n o n -leth al screen in g of th e brood sto ck can be p erfo rm ed w ith one p leopo d as the sam p le. A d iag n o stic PC R has also been d evelo p ed (Lightner, et al., 1996).

It is b elieved th at IH H N V m ay be tran sm itted v e rtic a lly from brood sto ck to th e ir p ro g eny (Lightner, 1983) but not proved beyond do ub t. IH H N V resistant penaeid sp ecies and e a rly life stag e s ca rry th e v iru s laten tly and tra n sfe r to m ore su sce p tib le sp ecies and life stag es e ith er via w ate r or in gested w ith in fected p raw n s (Bell and Lightner, 1984).

Effective co ntrol m easu res fo r IH H N V d ise ase are not know n. A vo id a n ce of th e v iru s th ro ug h q u aran tin e is stro n g ly reco m m en d ed (B ro o ke and Lightner, 1990).

Im p ro vin g farm m an a g em en t p ractices such as lo w ering sto ckin g d en sities, usag e of n u tritio n ally balanced feed s and stocking p o nd s w ith m ore resistant praw n species m ay red uce th e d ise ase of IHHN V.

T h e d isease caused by IH H N V co n tin u e s to be a ch ro n ic problem in all sh rim p g row in g c o u n trie sa n d in India sp o ra d ic in cid en ts have been rep o rted w ith o u t an y co n firm atio n .

Yellow Head Virus Disease (YHVD)

Lim su w an (1991) first noted y e llo w head d ise ase (YH D ) as a serio u s ep id e m ic of cu ltu red Penaeus m o n o d o n ad u lts in central Th a ilan d , S o u th -E ast A sia an d , later reported fro m Ind ia too.

(18)

Y H V is an R N A viru s (W o n g teerasu p aya et al., 1995) w ith a n u m b e ro f p ro p ertie s in co m m on w ith plant and crab rh ab d o viru se s (N and ala et al., 1997) Y H V has now been show n to be a corona v iru s based on seq u e n ce in fo rm atio n . It a ffe cts p rim a rily ju v e n ile s to sub adult p raw n s (B o o n ya ratp alin et al., 1994).

P raw ns w ith Y H D d isp la y y e llo w co lo u ratio n o f the dorsal ce p h alo th o ra x caused by the u n d erlyin g y e llo w h ep ato p an creas sho w ing th ro ug h a tra n slu ce n t carap ace. W ith in the ponds, in fected a n im als, u su a lly betw een 5 and 15g (Lin su w an , 1991), begin co n su m in g feed at an a b n o rm a lly high rate fo r several d ays until th e y stop feed ing entirely.

S u b seq u en tly, m o rib und p raw n s m ay be seen sw im m in g slo w ly near to th e edg e of the pond. By the third d ay m ass m o rtality o ccu rs and the entire crop is ty p ica lly lost (C h a n ta n a ch o o kin , e t a l., 1993).

Th ere is v e ry little gross p ath o lo g y asso ciated w ith YHD. A p art from pale yello w h ep ato p an creas and pale brow n gills no o th er sign co uld be n o ticed. H ow ever, this sign w a s also not seen in m o rib u n d an im als in Th a ilan d , su g g estin g th a t th is m ay not be a reliable sign o f YHD.

D iag n o sis o f y e llo w -h e ad d ise ase s is p re su m p tively based on th e p resen ce of clinical d iag n o sis and the h isto ry o f disease in cu ltu re facility, region on sp e cies (Lightner, 1996). A hem o cyte stainin g m ethod has been d evelo p ed fo r th e rapid d ia g n o sis of the early stag e s of Y H D (A n o n, 1992). This in vo lves takin g a sam ple o f h aem o lym p h from the ven tral or card iac sin u ses, d iluting the praw n h aem o lym p h in 10% seaw ater fo rm alin , fixin g it on a slide in m ethanol and stainin g w ith W rig h t's stain and geim sa.

H aem o cytes m ay then be in sp ected for n uclear p ykno sis and ka ryo rh e xis by bright field m icro sco p y (N ash, et al., 1995). A drop o f un d ilu ted h aem o lym p h m ay also be in vestig ated fo r Y H D using phase co n trast m icroscopy. D uring th e later stag e s of

in fectio n w h en the haem o cytes have been d ep leted , Y H D m ay be d iag n o se d , id en tifyin g ch ara cteristic b aso p h ilic p ykn o tic nuclei in rap id ly stained gill m o u nts (Flegel et al., 1995 a and b). Y H V in fectio n m ay be co n firm ed by TEM d em o n stratio n o f the non envelo ped v irio n s and fila m e n to u s n u cle o cap sid s in the cyto p lasm o f in fected cells.

A d iag n o stic RT PC R for y e llo w head viru s has been d evelo p ed alon g w ith a d iag n o stic D N A probe (W o n g te era su p a ya, 1996). W o rks are u n d e rw a y at C IB A to d evelo p a PCR based d iag n o stic kit fo r y e llo w head virus.

Y H V in T h ailan d is co n tro lled using closed and sem iclo sed syste m s (Lim su w an , 1991). In th e se system s, in take w a te r is treated before use w ith calciu m h yp o ch lo rite at a rate of 300kg /ha to kill w ild cru stacea n s th at m ay ca rry YHV. In sem iclo sed system s, no w ate r exch an g e take s place w ith in th e pond until 30-60 days post stocking w h ile in closed system s th ere is no w ate r exch an g e during cu lture cycle.

A d d itio n al p reven tive m easu res such as exclu d in g p otential carriers, not using fresh fee d s and not e xch an g in g w ate r fo r 4 days w h ere it is know n th a t an in fected pond in the area is d isch arg in g w ate r have proven effective ag ain st Y H D (Flegel et al., 1997).

Bacteria

Bacteria are o p p o rtu n istic p ath o g en s u su ally causing in fe ctio n s seco n d a rily in p enaeids.

T h e y are alw ays found in th e sh rim p body and p o n d w a te ra n d cause d ise ase o n ly w h en the shrim p is exp o sed to stress. A num ber of bacterial in fe ctio n s have been fo u n d in cu lture sh rim p from th e larval stag e to adult.

M ost of the iso lates from the in fected shrim p have been V ib rio spp. and o th ers in clu de A e ro m o n a s and P seu d o m o n a s spp.

Sh rim p in fected w ith bacteria show s d isco lo u ratio n o f the body, necrosis of a p p e n d a g e s and shell, ag g reg atio n of blood cells, lesio ns w ith the vital organs

(19)

and loss o f a p p e tite . Bacterial in fectio n s in penaeid sh rim p cau ses th ree fo rm s of d ise ase co n d itio n s like ero sio n s, lesio ns and sep ticem ia . W h en th e bacteria in fect body flu id s o f sh rim p , g en eral sep ticem ia and local lesio n s like h e p ato p an creatitis, o p th alam itis and e n teritis d evelo p . If the sh rim p is in fected by ch itin o vo ro u s bacteria w h ich are cap ab le o f shell lysis, blackened are a s or brown spo ts fo rm on the exo skeleto n . Bacterial in fectio n s are co m m o n in both h atch eries and g ro w o u t ponds.

Luminous Bacterial Disease

Lu m in o u s bacteria are m ore p ath o g en ic to eggs and larval stag es. It rarely affects ju v e n ile s and su b -ad u lts in cultured ponds to a sp ecific size. The lu m in o u s bacteria.

V ib rio h arveyi, d o m in ate the iso lates fro m in fected sh rim p . In fe cted larvae and ju v e n ile s b eco m e lu m in esce n t in the dark.

Lu m in o u s bacteria have also been isolated fro m sea w a te r w ith h ig h er salinity, esp e cially during sum m er. M ass m o rta lity often o ccurs in h atch eries during h eavy in fectio n . It has been o b served th at the g row th o f cu ltured P.m onodon is d ra stically a ffe cted w h en the lu m in o u s bacteria are p resent in pond w ate r b eyond 1x106 cells/m l. It is p o ssib le that th e bacteria release certain to xin s th at m ay retard the sh rim p grow th.

Vibrosis

V ib ro sis, also called bacterial sep ticem ia , is a syste m ic in fectio n caused by V ib rio spp. The d ise ase results in m ass m o rta lity o f larvae post larvae, ju v e n ile s and ad u lt sh rim p . The co m m o n sig n s are erosion of ap p e n d a g e e sp e cia lly an ten n a I rot, d isco lo u ratio n o f shell, red d isco lo u ratio n o f gills, h ep ato p an creas and a b d o m en , ag g reg atio n of h aem o cytes and h e p ato p an creatitis. The in fected sh rim p sw im d iso rien ted ly, b eco m e leth arg ic and so m e tim es e xh ib it vig o ro u s m o vem en t o f p leo p o d s. D uring m o rib und stag e the in fected shrim p b eco m e tra n slu ce n t w ith

o p a city (L ig h tn e ra n d Lew is, 1975).

V ib rio sis is caused by a nu m b er of V ib rio sp ecies o f bacteria in clu ding V .h arveyi, V .vu lnificus, V. p arah aem o lytiu s, V .alg in o lyticu s, V .penaeicida and several o th e r sp ecies of V ib rio (B ro o k and Lightner, 1990 and Ish im aru , et al., 1995). Th ere have been o ccasio n al rep o rts o f V ib rio sis caused by V. d am sela, V .fluvialis and o th er u n d efin ed V ib rio spp. (Lightner, 1996). V ib rio species are part o f th e natural m icroflora o f w ild and cu ltured p raw n s (S in d e rm an , 1990) and b eco m e o p p o rtu n istic p ath o g en s w h ere natural d efen ce m e ch an ism is su p pressed (B ro o k and Lightner, 1990). Even th o u g h th e y are a sso ciate d w ith m u ltip le aetio lo g ical a g en ts, som e v ib rio sp ecies or strain s o f certain sp ecies have been id en tified as p rim a ry p ath o g en s (O w en s and Hall- M en d ellin , 1989; Lavilla-P ito g o , et al., 1996 and de la Pena, et al., 1995).

D iag n o sis o f vib rio in fectio n is based on clinical signs and histo lo g ical d em o n stratio n o f rod shaped vib rio bacteria in lesio ns and n o d u les on h aem o lym p h . The o rg an ism can be isolated on vib rio selective or general m arin e a g a r plates. V ib rio sis m ay be id en tified rap id ly in th e fluid using the A P I- 20 N FT System w h ich in vo lves cu ltu rin g vib rio co lo n ies on A P l- N F T strip s and screening th e co lo n ies a cco rd in g to the d irectio n s (Lightner, 1996) on BIO LO G (an alte rn a tive to th e A P I System ).

V ib rio sis is co n tro lled by reg o ro u s w ate r m an a g em en t and san itatio n to prevent th e e n try o f vib rio s in the cu lture w ate r (B a tica d o s, et al., 1990) and to reduce stress on the p raw n s (Lightner, 1993). V ib rio in w ate r co lum n m ay be in activated by a 30 m inutes e xp o su re to 10 ppm ch lo rin e. A n tib acterials, w h e n , a re ad d ed in to g ro w o u t system , should be th ro u g h diet, at a co n cen tratio n required fo r in h ib itin g vib rio in h ae m o lym h . O nly p erm itted a n tib acterial co m p o u n d should be u sed, th at too by bind in g on to pelleted feed

(20)

w ith a good binder. A d m in istra tio n should be d o ne during tim e s of good co n su m p tio n of feed . Before h arvest, a w ith d ra w al period of 15 to 20 d ays has to be given to facilitate excretion o f the co m p o u n d s.

As p ro p h ylactic m easure, fo rm alin killed V.penaeicida and o th er V ib rio sp ecies have been rep o rted su ccessfu l in P. ja p o n ic u s and P. m o n o d o n by in co rp o ratio n in to m icro en cap su lated fee d s (Itam i, et al., 1991).

Im m u n o stim u la n ts have been rep o rted to have som e e ffect in co n tro llin g the m oralities asso ciated w ith V ib rio sis (Itam i, et al., 1996).

C reating o p tim u m en viro n m en tal co n d itio n s to the sh rim p is the high ly reco m m en d ed practice to help the anim al w ith o u t vib rio sis.

A p p licatio n of a n tag o n istic P seu d o m o n as (A n o n, 2 0 0 5 ) M icro co cu s sp. (Ja y a p ra k a sh et.

al., in press ) and vib rio p h a g e s (A non 2005) are the em erg ing p ro p h ylactic m easu res in the control of v ib rio sis

Shell Disease

It is also called b lack spo t d isease, co m m o n ly o b served in ju v e n ile s and a d u lt p enaeids.

A ffected sh rim p exh ib it brown to black n ecro tic lesio ns on th e shell. C h itin o vo ro u s bacteria like V ib rio spp. and A e ro m o n as spp. have been isolated from the lesions.

G ross signs o f the d ise ase in clu d e focal m elan izatio n on th e exo skeleto n and the un d erlyin g m em b ran es. The tissu e s rarely are affected in ad van ced stag e s o f in fectio n.

The sy m p to m s are rem o ved w ith the cast exo skeleto n . The a ffe cted sh rim p do not die from th is d ise ase alo n e. Fo rm atio n of lo calized n ecro tic pits and fluid filled blisters or h em ato m a, e sp e cia lly on carap ace can also be co n sid ered as part of shell disease.

Tall Rot

Several sp ecies o f ch itin o vo ro u s bacteria cause tail rot. T h e in fectio n is m ore prevalent w h en th e w a te r co n tain s h e a vy load of org an ic m aterial, w h ich fa v o u rs the grow th of p ath o g en ic bacteria, w h ich a ccu m u late s

at the pond botto m . In the early stag e of in fectio n , the e d g e s of uropo d turn b la ck a n d flu id -filled blisters form at the tip s leading to the necrosis and erosion o f the tail m argin.

T h e se parts reg en erate by the next m oult if the pond bottom q u a lity is im pro ved .

Chronic Tall Rot

In the ch ronic tail rot, n ecro sis and p u treficatio n result in the tail m uscle. This co n d itio n is u su a lly p receded by a general m uscle necro sis, w h ich is less serio us. Th ese sh rim p s u su a lly die w ith in a few days.

GIN Rot

M elan ized lesio ns d evelo p in the gill tissue during early stag e o f in fectio n and fin ally necrosis take s place, resulting in gill rot co n d itio n . S o m etim es the in n er lining of b ran ch io steg ite is also affected .

Bacterial Red Disease

It is caused by a grou p of bacteria b elonging to the g en u s V ib rio , A e ro m o n a s and P seu d o m o n as. Red d ise ase is also caused by a flo to xin s and e n viro n m en tal stress. A ffected sh rim p exh ib it red d ening o f tail, pleo po ds and legs. The size of h ep ato p an cereas reduces. M oribu nd sh rim p d evelo p a w h ite area u n d e r the exo skeleto n , at the base of the ro strum . Red d isease results in m ass m o rta lities also.

W ith the o n set of m ortality, the affected sh rim p q u ickly b ecom e red w h en co m pared to the h e alth y harvested shrim p.

Fungi

Fungi are o p p o rtu n istic p ath o g en s in a q u atic en viro n m e n t. M ay be b ecau se of the less ep id e m ic nature v e ry less e ffo rts are m ade to u n d e rstan d the e p izo o tio lo g y and e p id e m io lo g y o f fu n g al d iseases in shrim ps.

H ow ever, the know n fu n g al d ise ase s are listed below.

(21)

Fusariosis

Fu sario sis or black gill d ise ase is caused by the im p e rfe ct fungi Fusariu m solani.

All p en aeid s are p o ten tially su sce p tib le to it and is a result o f p o o r pond co n d itio n s.

T h e o rganism is u b iq u ito u s and p resent in soil and d etritu s. In fected a n im als sho w lesio n s on the gills, a p p e n d a g e s and / on cu ticle resulting even in lose o f ap p e n d ag e s.

M o rta lity m ay be a sso ciate d w ith the p ro d u ctio n o f m yco to xin es. The d ise ase is d iag n o se d m icro sco p ically on the basis of lesio n s and d a rk co lo u ratio n o f gills and the d em o n stra tio n o f fu n g al hyp hae and conidia w ith in the h aem o cytic n o d u les. In fectio n starts fro m co n id io sp o res p resent in soil and w a te r fo llo w in g in vasio n o f slig h t cu ticu lar w o u n d s. Extre m e ly d ifficu lt to control th ro u g h m ed icatio n and the best option is a vo id a n ce , reducing cro w ding and th ere by cu ticu la r injury.

Larval mycosis

Larval m yco sis is caused by P h yco m ycetes fu n g i such as Leg in id u m , S iro lp id iu m , H alip h th o ru s, Phythiu m , Lep to leg in ia.. Eggs and larvae o f m ost penaeid sp ecies are su sce p tib le to the fu n g i. In fected larvae b eco m e im m o b ile and sin k to th e bottom of th e ta n k w h en w ate r circu latio n is sto pp ed.

S e co n d a ry bacterial in fectio n m ay occur.

O n ce in fected the fu n g i g ro w u n restricted and e ve n tu a lly rep lace m ost of the prawn m u scle and soft tissu e. Fungi h yp h ae and d isch arg e tu b es are v isib le w ith in the body and zo o sp o re d isch arg e tu b es m ay be o b served protrud ing th ro ug h the cu ticle.

D iag n o sis is based on the d em o n stratio n o f d isch arg e tu b es w ith term in al vesicles co n tain in g zo o sp o re s. T h e fu n g i are in tro d u ced to h atch e ries by Brood sto ck and th e ir spo re can su rvive in seaw ate r for lo n g er p erio d s and read ily attach and encyst on th e cu ticle o f the eg g s and larvae. Larval m yco sis seld o m cau ses d isease in hatcheries w ith so und m an a g em en t p ractices. H o w ever

v a rio u s ch em ica ls such a sT rifu ra lin , M alach ite green . Fo rm alin, Potassium . P erm an g an ate and B en zalko n iu m ch lo rid e e ffectively d e stro y fu n g al sp o res in hatcheries.

Protozoa

Pro to zo an p ath o g en s are o f tw o broad cate g o rie s, th o se, w h ich in fect e xte rn ally and the ones, w h ich m u ltip ly internally. The external p arasites can in d u ce gill o b structio n (b ro w n gill) and low oxygen tra n sp o rt, an o rexia , reduced lo co m o tio n , low grow th and high su sce p tib ility to in fectio n by o p p o rtu n istic bacterial p ath o g en s. The m ain external protozoa are Z o o th a m n iu m , V o rticella, A n o p h rys, A cin ecta sp .Ep istylis, L a g e n o p h rys and Ep h elo ta. M ean w h ile G reg arin e s, M icro sp o rid iu m and H ap lo sp o rid iu m rep resent internal protozoa.

T h e se o rg an ism s need a second host fore co m p letin g the life cycle.

Microposridiasis

T h e d ise a se c o m m o n ly k n o w n a sc o tto n shrim p or m ilk shrim p is caused by three gen era of m icro sp o rid ian s such as A g m aso m a penaei, A m e so n (N o se m a) n elsoni and Plesto ph o ra.

T h e se u b iq u ito u s m icro sp ro d ian s infect ju v e n ile s and ad u lt cultured and w ild p enaeid s having a w o rld w id e d istrib u tio n . M ost m icro sp o rid ian s in fect and rep lace striated m u scle causing a ch ara cteristic o p aq u e w h ite ab d o m en . M ean w h ile A g m aso m a penaei in fe ct blood vesicles, heart, g o n ad s, gills, h e p ato p an crease, g ut and co n n e ctive tissu e as w ell as m uscle. In fected gonad ap p e ars w h ite and h yp ertro p h ie d w h ile m ultip le tu m o r like sw elling m ay be fo rm ed in the gills and su b cu ticu la r tissu es. D iag n o sis is by m icro sco p y and histology, w h ere m icro sp o rid ian are d etected . Transm ission is th ro ug h sp o res released in the face s of m arin e a n im als such as fin fish e s, w hich act as co n d itio n in g or in te rm ed iate hosts.

M icro sp o rid ia sis is not co n sid ered a m ajo r d ise ase o f cultured p raw n s. H o w ever o p acity

(22)

o f ab d o m in a l m u scu latu re is a m arketing problem .

Gregarines

The g re g arin es w h ich in fect sh rim p falls u n d e r th ree genera such as N em eto p sis, Parao p h io id in a and C ep h alo lo b u s. All p e n a e id s a re p otential h o s te s to th is parasite.

G reg arian s require at least tw o ho stes, a m o llu sc or an an n elid w o rm in ad d itio n to the cru stacea n s to co m p lete th eir life cycle.

Th is su g g ests th at the in fectio n can be avo id ed by rem o ving the in te rm ed iate host from the cu ltu re facility. Tro p h o zo ites and g am eto cyte s of th ese p arasites o ccu r in the leum an and are often attach ed to the lining o f the in testin e. T h is m ay lead to reduced ab so rp tio n o f food fro m in testin e and o ccasio n al in testin al b lo ckag e. T h e parasites can be d etach ed from in testin al co ntent prepratio ns.

Haplosporidians

H e p ato p an cre atic h a p lo sp o rid io sis is produced by h ap lo sp o rid ia. Even th o u g h no clinical signs o f h ap lo sp o rid ian in fectio n have been rep o rted in fected a n im als m ay show poor g ro w th . The p arasites are restricted to the h ep ato p an creatic tu b u le s of in fected p raw n s o ccu rrin g in the cyto p lasm o f the tu b u le epith elial cells causing h yp ertro p h y as the cyto p lasm is replaced by m ultip lyin g p lasm o d ia. In fe cted cells are u ltim ately d estro yed , releasing u n in u cle ate stag e o f the parasite in to the lum en. M o d erate to heavy h aem o cytic in flam m atio n and e n cap su latio n m ay o ccu r aro u nd h e a vily in fected tu b u les.

D iag n o sis is based on the d em o n stratio n of m u ltin u cleate plasm o d ia in epith elial cells of the hep ato p an creas. H ap lo sp o rid io sis is rare and in sig n ifican t eco no m ically.

NON INFECTIOUS DISEASES Ectocommensals

Filam en to u s bacteria and ciliate protozoans are co m m on e cto co m m e n sals of

sh rim p . R arely o ccu rre n ce o f a rth ro p o d e cto co m m e n sals has also been o b served . T h e se e cto co m m e n sals u su a lly do not cause sig n ifican t d am ag e to the b o d y su rface of the sh rim p and th e y sim p ly use the host as su b stratu m . So m etim es the ciliate and bacterial e cto co m m e n sals cau se resp irato ry and lo co m o to ry d ifficu ltie s w h en p resen t at a h ig h er density.

Filamentous Bacteria

Le u co th rix m ucor, a fila m e n to u s b acterium has been fo u n d to a ccu m u la te on the gills and a p p e n d a g e s o f sh rim p . T h is problem is o b served m ore often in larvae and post larvae stag e. In the a d u lt shrim p fila m e n to u s bacterial g row th is rarely o b served on gills, p leo p o d s and setae o f u ro p o d s. Each bacterial filam e n t is u n b ran ch e d w ith a chain of sq u are-sh ap ed cells. O vercro w d ed shrim p and w ate r enriched w ith n u trien ts are the co n d u cive facto rs fo r the grow th of bacteria.

The bacteria cause m o rta lities due to hypoxia and m ou lting in h ib itio n , w h en p resent in h ig h er density.

Ciliate Protozoans

Stalked p eritrich o u s ciliates like Epistylis spp., Z o o th am n iu m spp. and su ctro ian s like A cineta are th e co m m o n ecto co m m en sal p ro to zo ans. T h e y a ffe ct all the life stag e s of p en aeid s and fo rm a fu zzy m at on the shell, ap p e n d a g e s, gills and even eyes. Epistylis spp., u su a lly in fe sts shell and ap p e n d a g e s w h ere as Z o o th a m n iu m spp., p refers gills.

H eavy in festatio n results in the h in d ran ce of resp iratio n , lo co m o tio n and m o u ltin g . The sh rim p b eco m e restless and fre q u e n tly co m e to the e d g e s o f th e pond, e sp e cia lly in the m o rning . In fe statio n b eco m es severe w ith the in crease of sto ckin g d e n sity and organic matter.

Brow n gills d evelo p w h en th e gills a re severely in fested by Z o o th a m n iu m spp. It seem s that P.sem isulcatus is m ore su sce p tib le to Epistylis spp. and th e p leo p o d s are often m ore h eavily

(23)

in fected . Ep istylis d iffers from Z o o th am n iu m by lacking a central co n tractile m yo n em e in th e stalk.

Arthropods

A v a rie ty o f a rth ro p o d e cto co m m e n sals and fo u lin g o rg an ism s like iso p o d s, b arnacles and in sect eggs are o cca sio n a lly fo u n d to attach on to th e b o d y o f the sh rim p s, w hen th e m ou lting of w h ich has alm o st ceased . In P.m onodon an isop od parasite B o p yru s spp.

has been found to attach in b ran ch io steg al cham ber. Large sessile b arn acles grow on th e shell o f a d u lt sh rim p . S o m etim es aq u atic in se cts lay eggs on the b o d y su rface of the o ld e r shrim p.

Nutritional Diseases

N u tritio n al im b a la n ces result in a v a rie ty of d iseases, w h ich need fu rth e r in vestig atio n . H ow ever, the in cid en ce and m ortality, b ecau se o f them , is neg lig ible.

Black Death Syndrome

B lack Death or 'S h rim p S cu rvy' has been the w e ll-u n d e rsto o d and d escrib ed nutritio nal d e ficie n cy d isease. It o ccu rs rarely in exten sive and sem i-in ten sive cu ltu res but fre q u en tly o b served in in ten sive and su p er-in ten sive cu ltu res w h e re the natural food availa b ility is m in im u m . Sh rim p w ith Black Death exh ibit m elan ized lesio ns in the epith elial and co n n e ctive tissu e s o f th e cu ticle, eye stalks and gills.

Chronic Soft-Shell Syndrome

T h e ch ro n ic soft-shell syn d ro m e is of m u ltip le etio lo g ies. T h e ch ie f ch aracteristic is p ersisten t so ft-shell even during in term o u lt period (Fig. 15). T h e su sp ected cau ses o f the syn d ro m e are nu tritio n al d eficie n cies and po o r soil and w ate r quality. The w a te r q u ality in m any reg io ns o f the co astal zo n e o f India is co n sid ered low b ecau se o f p esticid e co n tam in atio n fro m ag ricu ltu ral effluents.

So ft shelled sh rim p are m ore su sce p tib le to su rface fo u lin g o rg an ism s. T h e y b ecom e

w e a k and die eventually. T h e se sh rim p s are not fit fo r pro cessin g and hence rejected in th e m arket or fetch low price.

Red Discolouration

Red d isco lo u ratio n w a s rarely o b served in th e ju v e n ile s o f pond reared P. m o n o d o n . It is caused by a flo to xin s and en viro n m en tal stress. Im p ro p e r sto rag e o f feed leads to th e g row th o f fungi th at p ro d u ce aflato xin s and caused red d isco lo u ra tio n . A ffected sh rim p exh ib it reddish d isco lo u ratio n of th e shell, gills and ap p e n d a g e s. M icrobial to xin s present in the spo iled feed or in the d etritu s o f p o nd s rich in o rg an ic m atter are resp o n sib le fo r the o ccu rre n ce o f the disease.

It is su sp ected th at high in puts o f lim e during pond p reparatio n (4 to n s/h a .) and v e ry high levels o f carb o n d io xid e (30-60 ppm ) to be th e cau se of th is co nd itio n .

Stress in d u ced red d isco lo u ratio n can be reversed if the a ffe cted sh rim p are taken out of pond w ate r and kept in aq u ariu m fo r a few hou rs. Red d isco lo u ratio n does not cause sig n ifica n t e co n o m ic loss. C a ro te n o id s are released from the affected h ep ato p an creas and are flu sh ed into the blood w h ich im p art red co lo u r to the b o d y o f the shrim p.

Exuvia Entrapment Disease (EED)

BED is ch aracterized by partial m o u ltin g or m o u lt in h ib itio n . It is co m m o n ly o b served in th e sub a d u lts of P m o n o d o n cultured in sub so il w ater. M o rta lity o ccu rs in the m iddle p hase o f m o u ltin g . The old exo skeleton a d h e re s to the u n d erlyin g skin and the a ffe cted sh rim p seem s lacking in stam ina to m oult. N u tritio n al im b alan ces and w a te r q u a lity d eterio ratio n have been the

su sp ected causes.

Blue Discolouration

Sh rim p w ith d istin ct or light blue d isco lo u ratio n w e re o b served occasio nally.

T h e tw o m ain reaso ns fo r th is co ndition w e re asta xa n th in d e ficie n cy in feed and

(24)

e n viro n m e n tally in d u ced stress.

ENVIRONMENTAL DISEASES

O ften, sud d en and w id e flu ctu a tio n s in w a te r q u a lity p aram eters like disso lved oxyg en, salinity, tem p e ra tu re and pH result in ab n o rm al co n d itio n s in shrim p.

Abnormal Gill Colours

Gill d iseases and a b n o rm al gill co lo u rs are the v e ry fre q u e n tly o b served p ro b lem s in pond reared sh rim p . In the affe cted -sh rim p , gills a cq u ire d iffe ren t co lo u rs such as black, brow n, red, o ran ge and yello w . Th ese co lo u r ch an g es in the gills are due to m any reaso ns like necro sis, p resence and actio n of p ath o g en s, a ccu m u latio n of soil p articles and o rg an ic m aterial, low d isso lved oxygen and pH, plankton die off etc. m o rta lity is u su a lly high w h en the gills are severely affe cted . H eavy w ate r exch an g e m ay abate the serio u sn ess of the co n d itio n .

Soil p articles and o rg an ic sed im en t a ccu m u late s on the pond bottom w h en the w a te r exch a n g e is m in im u m . A s th e shrim p alw ays stay at the pond bottom th ese dep o sit on th e gills w h ich results in brow n gill. It s fre q u e n tly o b served in the cu ltured ponds w ith low w a te r depth and h eavy g row th of b enthic alg ae.

Black gill syn d ro m e in penaeid sh rim p is v e ry co m m o n and has m u ltip le etio lo gies.

It is caused due to accu m u latio n o f soil p articles and dead plankton on the gills, Z o o th a m n iu m in fe statio n , p resen ce of toxic p o llu tan ts like cad m iu m , copper, am m o n ia and nitrate. Sh rim p w ith b lack gills lose resp irato ry e fficie n cy and the co n seq u en t m o rta lities m ay reach as high as 80 per cent.

Red gills are u su a lly o b served in su b -ad u lts of P.m onodon during nigh t tim e and early m orning hou rs w h en th e d isso lved oxygen is low. Th is co n d itio n is also fo u n d in the shrim p w ith red d isease. M o rtalitie s due to red gills are un co m m o n .

O ran g e gills are also fo u n d in the shrim p grow in g in p o nd s built on acid su lp h ate soils w ith low pH. Leachin g of acid ic w ate r from the pond d ykes during rains also causes oran ge gills. T h is w a te r co n tain s Jaro site cry sta ls o ran g e in colour, th e accu m u latio n of w h ich result in o ran g e gill co n d itio n . In th o se p o nd s w ith rich bloom of p h yto p lan kto n d o m in ated by d iato m s, shrim p d evelo p y e llo w gills due to accu m u latio n of d iatom s.

Muscle Necrosis

M uscle n ecro sis results in p en aeid s w h en sh rim p s are exp o sed to stress-in d u cin g co n d itio n s like low d isso lved oxygen, ab n o rm al levels o f tem p e ra tu re and salinity, o ve rcro w d in g e tc.T h e ch aracteristic sym ptom o f th is co n d itio n is w h itish ap p e ara n ce o f tail.

A ffected sh rim p m ay reco ver if th e co n d itio n is e a rly and stress is rem o ved . An ad van ced co n d itio n leads to a m ore serio u s ch ronic tail rot, w h ich is a lre a d y d escrib ed . M uscle necrosis w a s noticed to be m ore p revalen t in p o lycu ltu re p o nd s w ith Ind ian m ajo r carps.

Cramped Tall

C ram p ed tail or b o d y cram p is th o u g h t to be a result o f sudden ch an g e s in salin ity and tem p e ra tu re and in ternal im b alan ce of p o tassiu m ions. C ram p ed shrim p develo p d orsal flexu re o f the ab d o m en th at can not be straig h te n ed . Im p ro vin g w ate r q u ality p aram eters can reverse the co n d itio n . But the sh rim p w ith ad van ced stag e s can not m ove and lie on th e ir sides. T h e se sh rim p s w ill b ecom e an e asy p rey to can n ib alism . The exact cause o f th is co n d itio n needs fu rth e r in vestig atio n .

Blisters

H e m o lym o p h o m as, co m m o n ly called blisters, w e re v e ry fre q u e n tly o b served in pond reared sh rim p . Fluid-filled blisters form on the in n er and o u ter su rface o f the b ran ch io steg ite and ven tro -la te ra l p o rtio ns

About NICRA in CMFRl

«

CMFRI

nuoO oeAflJii nj)<s>nucn a J o I a JD s I

PREFACE

About NICRA in CMFRl

Acknowledgement

Contents

Business opportunities in aquaculture nutrition

Aquacufture nutrition

Present Status

SHRIMP DISEASES AND DISEASE MANAGEMENT

Introduction

Infectious Diseases

Viruses

Monodon Baculovirus (MBV) Disease

W hite Spot Syndrome Virus

Hepatopancreatic Parvo-like Virus

Yellow Head Virus Disease (YHVD)

Bacteria

Luminous Bacterial Disease

Vibrosis

Shell Disease

Tall Rot

Chronic Tall Rot

GIN Rot

Bacterial Red Disease

Fungi

Fusariosis

Larval mycosis

Protozoa

Microposridiasis

Gregarines

Haplosporidians

NON INFECTIOUS DISEASES Ectocommensals

Filamentous Bacteria

Ciliate Protozoans

Arthropods

Nutritional Diseases

Black Death Syndrome

Chronic Soft-Shell Syndrome

Red Discolouration

Exuvia Entrapment Disease (EED)

Blue Discolouration

ENVIRONMENTAL DISEASES

Abnormal Gill Colours

Muscle Necrosis

Cramped Tall

Blisters

nuoO oeAflJii nj)<s>nucn â J ô I â JD ^s I