diseases of fish

7/28/2019 Diseases of Fish

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P RE VE NT IO N A ND C ON TR OL O F C OM MO ND IS EA SE S O F F IS H I N P ON DS

Ex t e nsi o n Bu l l et i n N o 1 6 9

F is he ri es S er ie s N o 9

Published by

National Agricultural Extension and Research Liaison ServicesAhmadu Bello University

Zaria.


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ACKNOWLEDGMENT

A ll s ou rc es o f in fo rm at io n th at h av e b ee n p oo le d to ge th er a nd p ro pe rl ydocumented in bibliography of the bulletin are greatly acknowledged.S t a ff o f L i v e st o ck a n d F i sh er i e s Te c h no l o g y Tr a n sfe r P r o g r a mm e c o n t ri b u te di n o ne w ay or th e o th er to en su re t ha t t he m an us cr ip t o f t he b ul le ti n w as

produced with minimal errors. The Publication Review Committee, theP u b l ic a t io n a n d P u b l ic i t y P r o gr a m me a n d t h e M a n ag e m en t of NAE RL S a r e

g re at ly a ck no wl ed ge d fo r en su ri ng t ha t th e i nf or ma ti on c on ta in ed a remeaningfully disseminated through this bulletin.

Bolorunduro P.I.


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TABLE OF CONTENTSTa bl e o f C o nt e nt . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . 2A c kn o wl e dg me n t. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . 31 .0 I nt ro du ct io n. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . 42. 0 Importance of Healthy Fish Stock. .... .... .... .... .... .... .... .... .... 53. 0 Factors Promoting Ill Health and Diseas es in Cultured Fish.54 .0 C om mo n D is ea se s o f C ul tu re d F is h. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .55. 0 Preventive Management of Fish Diseases vis-a-vis

P o nd P l an n in g .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . 2 16. 0 G en er al H in ts t o F ar mer s. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 21B i bl i og r ap h y. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. 2 3

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1.0 Introduction

A ll l iv in g t hi ng s i n ce rt ai n c ir cu ms ta nc es a re s ub je ct t o i ll -h ea lt h a ndd i se as e s, a nd f is h is n o e x ce p ti o n. I t is p o ss i bl e t h at a t o n e t i me o r t h e o t he r th ef i sh f ar m er h as t o de a l w i th di s ea s e c o nd i ti o ns o f f is h in t he p o nd . To d o t h is

properly, it is necessary to know something about fish diseases that are likelyt o b e c o nt r ac t ed an d h o w t h ey ca n b e p r ev e nt e d o r c u re d. I t i s q u it e p o ss i bl e t ok ee p f is h i n a s ta te o f g oo d h ea lt h. G en er al ly mo st of th e f is h s pe ci es t ha t

perform well under culture conditions in Nigeria have very great resistance tod is ea se s s o l on g a s b ad h an dl in g, u ns ui ta bl e f oo d, po or wa te r q ua li ty,o v er c ro w di n g, o r o t he r a dv e rs e i n fl u en c es d o n o t w e ak e n t h em . To a v oi dd i se ase , t h e f i r st t h i n g t h a t a f a r m er sho u l d b e a r i n mi n d i s t o ke e p f i sh i n a g o o dc u lt u re ( o pt i ma l ) c on d it i on , s o t h at th e y c a n h a ve a g o od re s is t an c e w h en a nyi n f e ct i o n o c c ur s. M o st i n f e ct i o n s h o we ve r c a n b e a v o id e d t h r o ug h g o o dm a n ag e m en t p r a ct i c e s. I t is g e n er a l l y k n o wn t ha t c oc c u re n c e o f f i sh d i e ase i nfish ponds are quite few compared with occurences in the naturale nv ir on me nt . Th is m ak es t he m an ag em en t of p ar as it e d is ea se s o f fi sh e as ie r u n d er c u l tu r e . Co n d it i o n s t h a t d i sco u r a ge t h e p r o l if e r at i o n o f p a r asi t i es i n f i sh

ponds include lack of variety of fish found in ponds relative to natural waters,

partial or complete absence of the intermediate hosts of many parasites, andl a c ko f p e r i od i c d r a in i n g a nd d r y i ng o f t h e p o n ds. Co n seq u e nt l y i t i s p a r asi t e swi t h d i r ec t li f e c y c le s t h a t u su a ll y su r v i ve i n t he p o n ds.M o r e t h a n a n y o t h er t yp e s o f fi sh c u l t ur e , t h e p o n d f i sh er y pr o v i de s c o n di t i o nsf a v or a b l e f o r th e t r e at m e nt o f d i se ase s a n d f o r th e a p p li c a ti o n o f pr o p h yl a c t icm e a su r e s f o r th e e x c lu si o n o f th e p a r asi t e s o r sup p r essi o n o f i ts p r o d uc t i o n.I t i s t h e d e sir e o f e v e ry f i sh f a r me r t o h a v e a p r o f it a b l e v e n tu r e . No t h in g b r i n gsa f a rm e r t h at a ss u ra nc e t h an r ea r in g a h e al t hy s to c k o f fi s h w i th g oo d gr o wt hr a t e a n d a h e a lt h y p o nd e n v i ro n m en t .In general, fish dis ease can be caused solely by (or a combination of)m i c ro b e s ( g e r ms) , p a r asi t e s, a n d i m p r op e r p o n d m a n ag e m en t p r a ct i c es b y

f a r me r s. A p r e va l e nt d i se ase s c o n di t i o n i n p o n d wi l l l e a d t o sl o w g r o wth o f

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F i sh , u n at t r ac t i v e f i sh a p p ea r a nc e , g r a du a l o r su d d en p h y sic a l l o ss o f f i sh b yd e at h , e x tr a p r od u ct i on co s t t o f a rm er in tr e at i ng s u ch d i se as e s a n d o v er a lle c o no m i c l o sses i n p r o d uc t i o n.Information in this bulletin have been pooled together from different sources,c o up l ed w i th t h e a u th o r s e x pe r ie nc e t o a ss i st f i s h f a rm er s i n b ot h p re v en t iv ea nd cu ra ti ve a pp ro ac he s o f f is h d is ea se m an ag em en t t o e ns ur e a p ro fi ta bl efish-farming venture.

2.0 Importance of Healthy Fish Stock T h e n e ed fo r a h e al t hy fi s h s t oc k i n a p o nd is n o l e ss t h an t h e n e ed f o r a h e al t hyl i vi n g i n h u ma n s. E v er y f a rm er s h ou l d g i ve p r io r it y t o t h e h e al t h o f f i sh i n

ponds for the following reasons.i. For assurance of a profit oriented fish farming enterprise. Fish

d ea t hs d u e t o po o r h e al t h w i ll r ob a f a rm er n ot o nl y of i nt e nd e d

f i na n ci a l p r of i t, b u t a l so o f t h e t o ta l i n ve s tm e nt on t h e f a rm . T h issi t u at i o n c an b e p r e ve n t ed b y p r o pe r f i sh h ea l t h m an a g em e n tpractices in the ponds.

ii. To ens ure good growth of fish Stunted Fish (slow growing fish) areo ft en a d is ta st e t o m os t f is h f ar me rs a nd i n s om e i ns ta nc es s uc hexperiences have made some farmers pack up fish farming

practices. When fish are giving balanced and regular diets withn a tu r al f oo d s i n a g o od p on d en v ir o nm e nt , go o d g r ow t h w i ll b eassured.

iii. To prevent diseas e transmiss ion to man. It is know n that man canbecome infested with tapeworm by eating raw or insufficientlyc o ok ed f i sh . A l so a f a rm e r c an c o nt a ct d i se as e s o n t h e s k in b y

gaining access to an infested pond.

3. 0 F act ors Pro mo ti ng il l h ea lth an d Di sea ses i n Cu ltu red Fi shF a c to r s t h a t p r o m ot e i l l h e a lt h i n c u l tu r e d f i sh o r f a v o ur o c c ur r e nc e s o f f i sh d i se a ses a r e m a i nl y m a n a g em e n t a n d e n v i r o nm e n ta l l y b a se d . Wh en af i sh f a rm e r i s c a re f ul i n p r ev en t in g t h e o c cu r re n ce s o f s u ch c o nd i ti o ns ,

f i sh c ul t ur e w i ll b e a p l ea s an t e x pe r ie n ce w i th t h e e x pe c te d b e ne f it s . S u ch

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f a c t or s a r e m e n ti o n e d b e l ow

i. P o o r Wa t e r Q u a li t yWa t er i s t h e m e di u m f o r f i sh r e ar i ng . A f a rm er s h ou l d t h er e fo r e b ec a re f ul on th e s o ur c e o f w a te r f o r t h e p o nd . A l th o ug h w a te r q u al i tym an ag em en t i n f is h p on ds i s a w id e a re a, a f ar me r s ho ul d e ns ur e t ha t

pond water is fertile, less muddy (reduced clay particles), not too deepg r e en i n c o lo u r ( o ve r p r od u c t io n o f p hy t o p la n k t on s l e a di n g t o o x y ge n

depletion) and not offensive in odour (an indication of pollution).A g re at ad va nt ag e o f f is h c ul tu re i s t ha t t he f ar me r i s i n c on tr ol of th e

pond environment; therefore any observed anomaly in water qualityc an b e c or re ct ed . T hi s c an o nl y be d on e w he n th e f ar me r un de rs ta nd sthe ideal physical, chemical and biological characteristics expected of

pond water and water quality improvement practices.

ii. OverstockingI g n o r a n c e o n t h e p a r t o f a f i s h f a r m e r o n t h e s t o c k i n gd e n si t i e s/ st o ck i n g r a t es o f c u l t ur e d f i sh i n a p o n d e n v ir o n me n t c o u ldresult in either under stocking or over stocking of fish ponds. However

f ie ld ex pe ri en ce s h av e s ho wn th at mo re f ar me rs a re i nv ol ed i n o ve r stocking pond water with fish than under stocking. Over stocking ist h e a c t o f re ar i ng m or e t h an r eq u ir e d n u mb e r o f fi s h i n a u n it a re a o f

pond water. Dangers attached to this are numerous-over crowding, insufficient dissolved oxygen in pond water resulting in struggling forsu r v iv a l , c a n ni b a li sm d u e t o st a r vi n g , a n d m o r e i m p or t a n tl y p o ssib l e

epidemic, resulting in mass fish death.S t oc k in g d e ns i ty c a lc u la t io n s e x is t f o r a l l c u lt u re d f i sh , b u t a

2g e n er a l g u i de i s 5 - 1 0 f i sh p e r m f o r sp e ci e s t h a t r e a ch se x ua l m a t ur i t y2e a r li e r e .g . Ti l a p ia a n d a m a x im u m o f 5 0 - 6 0 f i sh p e r m f o r sp e c ie s

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t h a t d o n t r e p ro d u ce i n c a p t iv i t y ( e xc e p t b y h o r mo n e i n d uc e m en t ) e .g .cat fishes like Clarias, Heterobranchus and Synodontis , Under

2i n t en si v e c u l t ur e a t 10 0 f i sh / m a n d i n i n t e nse l y m a n ag e d b i o f il t r a ti o n2r e c yc l i ng sy st e m as m u c h as 3 0 0 - 40 0 f i sh m

iii. Erratic (Irregular) FeedingLike humans, fish need regular and consistent feeding in order to boostt he ir i mm un e s ys te m an d ma ke t he m le ss s us ce pt ib le t o di se as es :U n de r ex t en s iv e f i sh c ul t ur e s y st e m, f i sh a re o f te n l e ft t o th e m e rc y of

n a t ur a l f o o ds i n p o n d wa t er wi t h l i t t l e o r n o f e e d su pp l e me n t at i o n .A f a rm er s h o ul d c on s ci o us l y d iv i de f i sh f e ed s i n to 2 r a ti o ns p er d a y o r a t le a st a c o n sta n t d a i ly r at i o n i n ad d i t io n t o n a t ur a l f o o ds i n th e p o n d.I t is o f te n r e co m me n de d th a t f i sh s ho u ld b e f e d d a il y on a r a ti o n o f 4-8 % of f e ed s p e r bo d y we i g ht t o av o i d f e e d wa st ag e s. E x c essi v e f e e dsin pond encourages water polution.

iv. Nutrients Deficient Feeds.Ba l an c e d d i e t i s i m p or t a n t t o f i sh i n o r d er t o e n sur e t h e p e r f or m a nc e o f t he ir m et ab ol ic a ct iv it ie s. N ut ri en ts r ic h f oo ds a re s ec ur it y a ga in sts u sc ep t ib i li t y t o i l l h e al t h a n d d i se a se s . F i sh f o od s m u st b e r i ch i n

protein content and energy requirements. Fish normally grow well on

f e e d c o n ta i n in g 3 5 - 4 0% c r u de p r o t ei n . Ot h e r r e c o mm e n de dproximate composition of fish feeds include minerals and vitamins( 3 2 - 33 % ) , f a t s ( 11 % ) a n d c a r bo h y dr a t e ( 6 - 1 0% ) Co m mo n f e e dst u ff sa va i la b le t o f a rm er s i n cl u de g r ai n /c e re al b a rn s ( e ne rg y s u pp l em e nt s )a n d b l o od m e a l , g r o un d n ut c a k e a n d c o t to n se e d c a k e ( p r o te i n f e e ds) .

v. O v e r f e r t il i z a ti o n

I n a s m uc h a s i t i s n ec es sa ry to en su re w at er qu al it y i mp ro ve me ntpractices to boost pond activities in natural foods, a farmer should bec a r ef u l e n o ug h n o t t o c a u se a l g al b o o m ( a n i n d ic a t i on o f o v e r f e r ti l i ze d

pond water). A fish pond that has high density of algae isn o r ma l l y c h a ra c t er i z e d wi t h d e e p g r e e n c o l ou r a t io n . S u c h

s i tu at i on e nd a ng er s t h e f i sh he al t h s i nc e t h er e w i ll be r a pi d d e pl e ti o n

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o f d i sso v ed o x yg e n i n t h e p o n d l e a di n g t o b e h av i o ur a l str e ss,r e st le ssn ess a n d hi g h susc e pt i b i li t y t o d i se ase s a n d so m e t i m es, d e at hof fish.I n th e u se o f in or ga ni c f er ti li ze rs a nd o rg an ic m an ur es f or p on d w at er f e r t il i z at i o n , st a n da r d r a t e s o f t h e ir a p p l ic a t i on s e x i st. A f i sh f a r m er sh o u ld f a mi l i a ri z e h i m sel f wi th su ch r at e s I n f or m a t io n on t h is c a n b eo b t ai n e d f r o m F i sh er i e s E x t en si o n st a ff i n e a c h l o c al i t y.

vi. Incidence of Predators and Wild Fish

P r e di a t o rs a r e n a t ur a l e n e mi e s o f f i sh . Ap a r t f r o m c a u sin g f i sh d e a thd ir ec tl y b y p re yi ng on th em , t he y a ls o a ct as i nt er me di at e h os ts f or

parasites that introduce diseases to ponds. Fish ponds should be keptf r ee f r om p r ed a to r s a n d w i ld f i sh . T h is c a n b e a c hi e ve d b y p e ri o di cd ra in in g of t he p on ds a nd t re at in g th em w it h q ui ck l im e o r ro te n on e.S u c h t r e a tm e n ts wi l l k i l l m o l lu se s, c r u sta c e an s, a n d t h e i r e g g s a s we l la s e gg s o f pa ra si te s. P is ci vo ro us b ir ds s ho ul d be k ep t aw ay f ro m fi sh

ponds to prevent them seeding ponds with the eggs of potentiallyd an g er o us p a ra s it e s. E x am p le s o f pr e da t or s a r e s h ow n in F ig u re 1P r e da t o r s c a n b e c o n tr o l l ed b y r e g ul a r cl e a ni n g o f p on d s si t e s, f e n ci n gt h e p o nd , p r ev e nt i ng f l oo d w a te r s, fr o m e nt e ri n g t h e p o nd an d b y

physically elimination using traps or point blank killing.

F i g 1 . S o me p r ed a to r s o f f i sh .

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vii. Bus hy and Unhygienic Pond EnvironmentB u sh y p on d e nv i ro n me nt s a r e h i de o u ts f o r p re d ic a to r s, w h i ch i n t u rna re i nt er me di at e h os ts t o p ar as it es . U nh yg ie ni c p on d e nv ir on me nt

often reflect in environmental pollution. When pollution occurs in af i sh p o nd e n vi r on m en t , t he e nt i re f i sh s t oc k c a n be m ad e s u sc e pt i bl e t od is ea se s o r i ns ta nt de at h. Fi sh fa rm er s s ho ul d a s m uc h a s p os s ib leg ui de a ga in st do me st ic , a gr ic ul tu ra l a nd i nd us tr ia l p ol lu ti on s f ro mgaining access to pond water.

viii. Rough Handling of FishM a n ag e m en t pr a c t ic e s i n v o lv i n g h a n dl i n g o r tr a n spo r t a ti o n o f li v ef i sh (e sp ec i a ll y f o r st o c ki n g ) r e q ui r e s g r e at c a re t o p re v e nt i n j ur i e s t ofish skins. Wounds on skin facilitate diseased condition. Even whenf i sh a r e b ee n t es t s a mp l ed , g re at c a re m u st b e t a ke n t o mi n im i ze b o dyi nj ur ie s t o t he f is h s in ce o ne o f t he m os t c om mo n r ou te t o i nf ec ti on i s

through the skin, particularly when damaged.

4.0 Common Diseases of Cultured Fish

D is ea se s a re a n u nw ho le so me c on di ti on s c au si ng s ic kn es s, a nd /o r death. They are great threat to profitable fish production.T he n at ur al a bo de o f f is h i s w at er an d t hi s m ak es f is h s us ce pt ib le t o

d i se a se c on d it i on , e sp e ci a ll y s i nc e w a te r m ed i um ( w he t he r r iv e r,stream or dams) is the recipient of industrial, agricultural and domesticeffluents and drainages.Ho we ve r u n de r c u lt u r e c o n di t i o n, a f a r m er c a n ma n i p ul a t e o r m a na g et he f is h p on d en vi ro nm ent to redu ce th e i nci de nce of di seas es .Co m mo n d i se ase s i n fi sh c u l tu r e c a n b e c a t eg o r iz e d i n t o t h e f o l l owi n g :

I. Diseases caused by Microbes.Mi cr obe s ar e g er ms th at c ann ot b e s een w it h t he nak ed e ye s,

but attack fish when condition that promotes their occurrencese xi s t. D i s ea s es c au s ed b y m i cr o be s a r e b a ct e ri a l, v i ra l a n d

fungal diseases.

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2. Bacterial diseasesBa c te r i a a r e f o u nd p r a c t ic a l ly e v e r y wh e r e, i n wa t e r a n d a i r, o n

plants and in the bodies of men and animals. Most of them,h ow ev er, a re s ap ro ph yt es ( i. e. t he y f ee d on d ea d o rg an icm at er ia l an d no t li vi ng t is su e) w ho se a ct iv it ie s a re o f gr ea ti m p or t a nc e i n n a t u r e .Fo rt un at el y, mo st b act er ia l di se as es s how ch ar ac ter is ti cs y mp t om s , w h ic h e n ab l e t h ei r e a sy r e co g ni t io n w i th s u ff i ci e nt

a c c ur a c y. Ba c t er i a l i n f ec t i o ns m a y o c c ur i n t h e i n t e rn a l o r ga n s,i n t h e m u sc l es a n d i n t h e s k in , i n cl u di n g t h e f i ns .Fishes that are not weakened by bad conditions, or byinfections with other parasites, generally have a greatresistance to bacterial infections.Factors Promoting Bacterial Infection.i. Overstocking, i.e. overcrowding of fish in pond water ii. Wounds on fish flesh. Wounds promote bacterial

i n f e ct i o n o n f i sh d e c re a se t h e ir r e si st a n ce t o d i se ase s.iii. Presence of dead organic matters in the pond. Too

m u c h d e a d o r ga n i c m a t er i a l s d e c ay i n g i n t h e wa t er ar e

primarily due to activities of bacteria and fungi. Fishpresent in such pond environment can easily beinfected.

iv. Low dissolved oxygen content in water. This situationi s c ha ra ct er iz ed b y r es tl es sn es s o f t he f is h. I n s uc hc o nd i ti o n, w h il e s t ru g gl i ng w o un d s a r e o f te n in f li c te d

o n f i sh f l esh m ak i n g th e m su sc e pt i b l e t o b a c te r i a l a n dviral infections.

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Symptoms of Bacterial Infection.i. Darkening of fish skinii. Slow, sluggish or weak movement in water.

iii. Loss of appetite i.e. fish not active in feedingiv. Fis h cluster near water inlets of ponds and even try to

jump out of the pond.v. Red/brown spots on fish skin.vi. Visible red streaks (lines) at the base of the fins.vi i. S wel li ng of the abd om en w it h pr otr udi ng s cal es .

Prevention/Control Measuresi. Stock fish at recommended ratesii. Dont apply too much fertilizer in the pond to avoid

e x c essi v e a l g al b lo o m a n d t h e c o n se q u en t de p l et i o n o f dissolved oxygen.

iii. Feed fish at recommended rates with good qualityfeeds.

iv. Ensure a clean pond environment.F o r tr e a t me n t of so m e b a c te r i a l d i se ase s se e Ta b l e 1 .

Ta b l e 1 . Tr e a tm e n t o f s o me B a c t e ri a l D i s e a se s o f F i s h

Disease

Sympt oms

Treatment

1 . C o t t o n w o o l o r

M o u th f u ng u s .

C a u s a t iv e a g e n t:

M yxobactor ia

Chondrococcus

columnaris

or

C y t o p h a ga c o l u m n ar i s

O c c u rr e n c e o f f u n g u s-

l i k e co t t o n w o o l

g r o w t h o n t h e m o u t h

of f ish.

A p p e ar a n c e o f

w h i t i sh- g r e y s p o t s a t

t h e h e ad , f i ns , g i l ls a n dbody.

S w ol l en l i ps w i th

macer ations.

F i s h l o ss e s a p p e t it ea n d m o v e s s l u g g i s hl y.

Apply 5- 10mg/l of

Chlor amphenicol

Dip f ish in Copper

S u l p h a te s o l u t io n f o r

1 - 2 m i nu t es o r

M a l a ch i t e g r e e n fo r

10- 30 seconds

F o r e n tr i e s p o n d a d d

1 mg Copper

S u l p h a te p e r l it r e .

2 Ta i l a n d F i n r o t .

C a u s a ti v e a g e n t

B acterioses

pinnarum

or A eromonas sp

P u tr e fa c ti o n o f t h e t a il

or gills

Apply

Chlor amphenicol

50mg/l f or up to 24

h o u r s o r 8 0 mg / l f o r

n o t m or e t h an 8

h o u rs o r a dd

Chlor amphenicol tof i sh f oo d a t a r a te o f

1mg per gr am of f ood


12/23

2. Viral DiseasesVi r us e s a r e i n fe c ti o us a g en t s o f va r yi n g s m al l di m en s io n s t h atm u lt i pl y o n ly wi t hi n t h e l i vi n g c e ll of a h o st an d w h ic h a r e

m or e t in y th an b ac te ri al a nd a s s uc h no t vi si bl e t o th e n ak ede ye s. E xa mp le s o f vi ra l di se as es a re a bd om in al d ro ps y an dswim bladder inflamation.(Fig 2)

Fig 2. Abdominal dropsy and swim bladder inflamation

Symptoms of Viral Diseasesi. Multiple ulcers in various parts of the body especially the tail

region.

ii. Slow and sluggish movement resulting in death of fish ma inse v er e c a ses.

Prevention/Controli. Practice good pond sanitation and keep a hygienic pond

environmentii. Ensure regular feeding of fish.iii. Ensure proper stocking and appropriate pond fertilization.

T h is w i ll p re v en t ba c te r ia l an d fu n ga l di s ea s es t h at c ou l dpromote viral diseases.

iv. En su re t hat fi sh to be s toc ked wi th ex is tin g r es id ent pop ul ati on

o f fi s h i n a p o nd a re v i ru s f r ee .

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v. Ensure g ood water qualityvi. Remove dead fish (corpse) from pond water immediately to

discourage rapid infection.

Tr e a tm e n ts o f som e c o m mo n di se a se s o f f i sh a r e g i v e n i n Ta b l e 2 .

3. Fungal DiseasesT he se a re d is ea se s c au se d b y f un gi . F un gi ar e l ow f or m o f p la nt l if ec ap ab le o f p ro du ci ng d is ea se s. F un ga l i nf ec ti on s a re g en er al ly

secondary and indicative of other problems. They are hardly found onh e a lt h y f i sh . S e v er a l f a c t or s a r e i n v ol v e d i n t h e d e v el o p me n t o f f u n ga li nf ec ti on i n fi sh . T he se f ac to rs w hi ch a ff ec t bo th t he f is h an d t he p on da nd it is a c om bi na ti on of fa ct or s r at he r t ha n a ny si ng le c on di ti on ,which ultimately leads to infection.

Co n d it i o n s t h a t p r o mo t e f u n g al di se a se s a r e :

i. Stress condition of fish population in pond due toovercrowding.

ii. Poor handling of fish at stocking or when practicingi n du c ed b r ee d in g e x er c is e l e ad i ng t o s k in d am a ge o r wounds.

iii. Starvation in pond causing fish to feed on rotten,

mouldy feed.

12

Table 2: Treatment of some viral diseases

Disease Symptoms

Treatment

1. Dropsy

C a u sa t i ve a g en t :

Aeromonas punctata

Excessive

abdominal swelling

Inflamed bloodvessel showing

reddish colour

Apply

Chloramphenicol 13mg/l for longer period

or 50mg/l for 24 hours

only

2. Swimbladder

inflammation

C a u sa t i ve a g en t :Aeromonas sp

L o ss o f a p p et i te

P o or r e s po n se t o

flight stimuli

* D i s tu r b e d b a l a n c e i n

swimming

Swollen and cloudyswim bladder

ApplyC hl or am ph en ic ol 1 5 -

20 mg/l for 24 hours


14/23

iv. Malnutrition due to unbalanced diet.v. Unfavourable climate changes causing fish to be

st r e sse d a nd r e st le ss e sp e ci a l l y h i g h t e m pe r a t ur e .

vi. Preponderance of bacterial or viral conditions in fish.

General Symptoms of Fungal Diseasesi. Appearance of characteristic cotton wool like growths

on t he aff ec te d pa rt o f t he b od y es peci all y du e t o

wo u n ds r e su lt i n g f r o m p o o r h a n d l i ng p r o ce d u r es.ii. Fish feeding on mouldy feeds.iii. Observable skin and gill lesions.

Prevention/Control Measuresi. Stock fish at the recommended rates in ponds.

ii. Handle fish carefully at stocking or sampling period.iii. Avoid erratic feeding practices and feed fish on

balanced ration.iv. Ensure good pond sanitationT h e t r ea t me n ts o f t w o c o mm o n f u ng a l d i se a se s i n f i sh c u lt u re

a r e sh o wn i n Ta b l e 3 .

13

Ta b l e 3 . Tr e a tm e n t o f so m e F u n g al D i se a s e s o f Fi s h

Disease Sympt oms Treatment

1. Saprolegniasis

C a u s ta t i v e a g e nt :

Saprolegnia

parasitica

2. Gill rot or

Branchiomycosis

C a u sa t i v e a g e n t:

Branchiomyces sp.

Cotton wool like

infection on skin and

gills

C i r c ul a r l e si o n s o n

skin

Gill necrosis

Fusion of gill lamellae

G e n e r al w e ak n e s s o f

fish with sluggish

movement.

D r a i n a n d li m e t h e

pond

D ip f is h i n M al ac hi te

green solution for 30

seconds

T r e at m e n t i s r a t h e r by

prevention

Strict pond hygiene

I m m e d i at e r e m o v al o f

d ea d f is h

Avoid overfeeding


15/23

II. Diseases Caused by ParasitesM o st f is h po p ul a ti o ns i n th e w i ld a re i n fe s te d w i th p ar a si t es b u t i n th eg r ea t ma j or i ty o f c as e s, n o si g ni f ic a nt h ar m ap p ea r s t o b e c a us e d t o t h e

h o st f i sh . P a r asi t e s i n wi l d f i sh a r e o n l y f r e q ue n t l y n o t ic e d wh e n t h e ya re s o o bv io us s o a s t o l ea d t o r ej ec ti on of th e f is h b y f is he rm en o r c u st o me r s. I n f i sh c u lt u re , h ow e ve r, p a ra s it e s o f te n c au s e s e ri o uso ut br ea ks o f d is ea se s. Pa ra si te s a re o rg an is ms t ha t l iv e i n o r o n o th er a n im a ls k n ow n a s h o st s . T h ey ex t ra ct fo o d f r om th e h o st by s uc k in g

blood or eating the tissues. Internal parasites (endo-parasites) of fishi nh ab it t he d ig es ti ve t ra ct o r o th er o rg an s i n t he b od y w hi le e xt er na lparasites (ecto parasites) attached themselves to the gills, skin, and finso f t he f is h. E xa mp le s o f e nd o p ar as it es a re a sc ar id s a nd t ap ew or ms ,w h il e e c to p a ra s it e s i n cl u de l i ce , f l ea s , l ee ch e s a n d dr a go n f l y n y mp h se .t .c ( Fi gu re 3 ).

F i g 3 . C a rp i n fe s te d w i th l e ac h es

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16/23

S o me c o mm o n p a ra s it i c d i se as e s o f f i sh , t h ei r s y mp t om s a n ds p ec i fi c t r ea t me n ts a r e o u tl i ne d b e lo w i n Ta b le 4 .T h e c o mm on p a r as i ti c d i se a se s a r e m ai n ly p r o to zo a n d is e as e s( I c h th y o ph t h i ri a si s, E p i sty l i s, M i l k sc a l e a n d Tr i c h od i n i asi s) ,Tr e ma t od e ( E ye f l uk e) , C e st o de s ( Ta pe w o rm s ), M o n og e ne t icF l u ke s, a n d Cr u st ac e a n d i sea se s ( An c ho r wor m s a n d f i sh l i c e) .

F a ct o rs t h at p r om o te P a ra s it i c D i se as e s a r e:

i. Access of most fish predators to ponds environment.ii. Decomposed fish carcasses in water. This encourages

spread of parasites to healthy fish.iii. Bus hy pond environment that harbours predators.iv. Favorable environmental conditions enabling mass

reproduction of the parasites.

Ge n er a l S y m p to m s o f P a r a sit i c I n f e ct i o n si. Skin lesion and peelingii. Darkened coloration of skiniii. Fish rubbing flesh against the sides of the pond wall

d u e t o s e v er e i r ri t at i oniv. Restlessness of fish in water v. Loss of appetite and retarded growthvi. Excessive slime production on the skin and gillsvii. Mass death of fish.

Prevention/Control Measuresi. Prevent pond from being overgrown with weeds.

P re da to rs o f f is h e as il y g ai n a cc es s t o p on ds t ha t a rebushy.

ii. Control predators by killing

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16

Ta b l e 4 : Tr e a t me n t o f so m e p a r a si t i c d i s e a se s o f c u l t ur e d f i sh

D isease Causati ve Agents Symptoms Treatment

1 . I c h th y o p h th i r ia s(White sp ot

disease)

Ichthyopthirius

m ultifilis Thickened outer

layer of fish skin

E x c es s i ve m u c u son skin

W h it e s p ot s o v er skin

R e s tl e s sn e s s o f f i s h

by rubbing body on pondwall

Apply 25 mg/lof Formalin (37%

Formaldehydre) inpond of 166 gm/l in

tank.

Dip fish inM a la c h it e g r e en o f 1mg/l for 10 -30s e c on d s a t 3 d ay sinterval

2 . E p is t yl i s d i se as e

Epistylis sp

Thick white dirt yy e l lo w p a t ch e s o r st r e ak s

on scales, fins or entirebody

Dip infectedfish in salt solution

of 7000mg/l for atleast 5 days

3 . M il k s ca ledisease

Myxobolus

notam igoni

W h it e c y st s w i thm i l ky a p p ea r a nc e o nr a i s es s c a le t h a t c a neasily rupture

Dip infect edfish in salt solutionof 7000 mg/l for atlast 5 days

4 . T r ic h o d in i a si s

Trichodina sp

Irregular whitepatches on head or body

S l u g gi s h n es s a n drefusal to eat

ApplyFor malin andM alachite green aswith wh itespotd i s ea s e t r e at m en t .

Avoidovercrowding of fish

5 . E ye f lu ke

D iplostom ulum

spathaceum

O p aq u e e y e l en s

Heavy infestation

may result in blindness

R em o ve a n d

destroy infected fish

6 . Ta pe w or m

Liguala intestinalis

Swollen stomach

Fish b eco mes

restless, losses weight orbecome inactive

Apply 2.7kg of

B u t yl o x i de p e r t o n n e o f f e e d . F e e dfish at 3% bodyweight for 3-5 days

Drain pondand disinfect withCalcium oxide

7 . F l uk e d i se as e

D actylogyrus sp

H eterophyes sp

R e s tl e s sn e s s a n d

discomfort

Rubbing body on

pond bottom

Apply

For malin o r M al ac hi te g r ee n a sin white spot diseasetreatment.

8 . A n c h or w o r m s

Lernea sp

L e s io n s o n b od ys u r r o un d e d b y p a t c he s o f

fungus

P a r as i t e b u r r o winto fish skin and spreadl i k e t h r ea d s

Drain pondand disinfect with

l i m e f o r 1 - 2 w ee k s

R em o ve a n ddestroy affected fish

9 . F is h l ic e

Argulus sp

F i s h i s r e s tl e s s

Red spot at point of infection on skin

M a s s m o r ta l i ty

Drain anddisinfect with linefor 1-2 weeks

ApplyFor malin o r m a l ac h i te g r e en a s

in white spot diseasetreatment


18/23

iii. Remove fish corpses from pond water promptlyiv. Apply lime at recommended rates. Limes are excellent

pond disinfectants.

v. Prevent floodwater (from other sources) from gettingt o t he p o nd .

Treatment of Parasitic DiseasesCu l t ur i n g f i sh i n p o n ds p r o v id e s c o n di t i o ns t h a t a r e f a v ou r a bl e

f or t he t re at me nt o f d is ea se s a nd f or t he a pp li ca ti on o f prophylactic measures for the exclusion of the parasite orsuppression of its reproduction.In most cases parasite infested fish in aquaculture can beh a n dl e e i n t he f o l l owi n g wa y s:i. By baths with recommended chemicals. This frees the

fish of ectoparasites.ii. Drying of the ponds in hot dry season to expose the

parasites/predeators and thereby disrupting their lifecycles.

iii. Treatment of pond bottom with lime to disinfect the

pond and eradicate the parasite.iv. Apply recommended chemical dosage (quarantine) ons i ng l e p o nd s o r e nt i re f a rm .

v. Extermination of wild fishes which might be carriers of t h e d i se a se a g en t s

vi. Shooting of predators.

vii. Building up parasitic disease resistance ability of f ishby stimulating their growth rate and improving theirc o n di t i o n b y g o o d f e e di n g . S l o w g r o wth a n d p o o r c o n d i t i o n o f f i s h a r e k n o w n t o f a v o u r m a s sreproduction of parasites.

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19/23

III. Management related diseases.These are disease whose occurrences are promoted by any act of m i sma n a ge m e nt o n t h e p a r t o f t h e f i sh f a r m er s. Su c h a c t s r e su lt i n n u t r it i o na l

problems, poor water quality and low dissolved oxygen availability.Ta bl e 5 sh ow s s om e c om mo n n ut ri ti on al an d e nv ir on me nt al ac to rs t ha t

promote diseases conditions in fish culture and the specific treatmentrecommended

18

Ta b l e 5 : S h o ws N u t r it i o n al a n d E n v i ro n m e nt a l p r o b le m s d i s e as e c o n d it i o n s i n c u l t ur e d

fish and their treatmentProblem Cause Symptoms Treatment

1.Starvation(absolute

Nutritional

deficiency)

M anagement neglect Darker than normaland softer flesh

L a rg e h e ad w i th t h inbody

P a le g i ll s a n d w ea r y

parasite burden

F e ed f i sh r e gu l ar l y a tr e c o mm e n d ed r a t es

E ns ur e r at io n i s o f balance diet with high

proportion of proteinand vitamins

2.Nutritional

cataract

Deficient vitamin and

protein in feeds E y e l e si o n

O p a q ue e y e s o r

c o m p le t e b l i n dn e s s

R at i on s h ou l d b e r i ch

i n p ro t e in s a n d

vitamins3. Acidicwater

L ow P H ( Be lo w 5 ) F i s h s k in c o v e r e d w i t h

whitish films, gills turnbrownish

M ortality of fish.

A p pl y 5 0 0k g C a co 3per hectare of pond

4. Alkaline

water

High PH

(Above 9) M ortality of fish. A pp ly l im e i n

sufficient quantitya cc o rd i ng t o P H l e ve l .

5. Lowerdissolved

oxygen (DO)

Over fertilizationcausing algal bloom

F i s h r e g u la r l y c o m e

out to gasp for

a t m os p h e ri c a i r.

M a s s m o r t al i t y o f f i s hwith wide-open mouth

a n d g il l s w i de p a rt .

D ra in p on d a nd c ha ng e

water.

A e ra t e t h e p o nd i f d e vi c e i s a v ai l ab l e o f f l u s h f r e s h w at e r b y

h i gh v e lo c it y i n to t h epond.

6.Gas-bubbledisease

Super saturation of pond water with

nitrogen or oxygen

Sudden temperature

gradient

Dark colour of eyes,s k i n , g il l s a n d m o u th

of adult fish

In larval fish,

protruded yolk sac.

E n s u re p r o p er a p p l ic a t io n o f

r e co m me n de d r a te s o f f e e d s, f e r t il i z er s a n d

lime

E l i mi n a t e p o n d w ee d s .

7. Water-boreirritants

P r e s en c e o f c e m e n tparticles, dust or silt

a n d am m o n ia i npond water

C o n s pi c u o us g i l ldamage.

R e s tl e s s ne s s a n d

rubbing of fleshagainst pond walls.

Prevent pollutantsf r o m g et t i ng t o p o n d

water.

8. Traumaticinjuries

Rough handling onfish in test cropping

or relocation

S k i n i nj u r i es f r o m

harvestingappliances

L e s io n s o n f is h

Reduced metabolic

activities

H a nd l e f i sh w i th c a r e

E n su r e p o nd i s c l ea r ed

of woundingappliances.


20/23

C o nd i ti o ns t h at fa v ou r t h e o cc u rr e nc e o f m an a ge me n t r e la t ed d i se a se s i nf i sh c u l t ur e i n c l ud e :

i. Lack of technical know-how on management practices by fishfarmers.

ii. Erratic p ond feeding.iii. A lgal boom i. e. pond water overgrown with algae.iv. Rough handling of fish.

v. Bushy and unhealthy pond environment.

General symptoms of management related diseasesi. Stunted fish growthii. Slow, sluggish and weak fish that may go off-feediii. Deep green colouration of pond water

iv. Bud smelly pond water with copious air bubbles on water surfaceearly morning and late evening.

v. Eas y s usceptibility of fis h to diseases and parasites

Prevention/Control Measures

i. Se ek tech ni cal as si st an ce of ex tensio n wo rk er s on po ndmanagement practicesii. Follow recommended rates of pond feeding, fertilization and

limingi ii . E ns ur e t he ap pl icat io n o f g oo d q ua lit y f ee ds tu ff s i n p on d f eed ingiv. Ensure overall hygienic pond environment

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21/23

5 .0 P re v e nt i v e Ma n a ge m e nt o f f i sh d i se ase s v i s- a- v i s p o n d p l a nn i n g .

R i gh t p l an n in g a nd c o ns t ru c ti o n of p o nd s i s v e ry i m po r ta n t in f i s h cu l tu r e.

W he n p ro pe r p la nn in g i s n ot pu t i n p la ce a t t he i ni ti al st ag e o f p on d s it ese l ec t i o n a n d c o n str u c ti o n , se v er e c o n seq u e nc e s m a y b e f a c ed l a t er.T h e a r r a ng e m en t o f p on d s i n c ha i n s wi t h i nt e r- d e pe n d en t su pp l y a n d d ra i n ag eo f w at er, la ck of sp ec ia l p ur po se p on ds , c ho ic e o f a n u ns ui ta bl e s ou rc e o f water, disregard of the temperature conditions, and many other inadequacies

a r e c o m mo n to m an y po n d f i sh er i e s, a n d e n h an c e d i sea se c o n di t i o nsI n p la nn in g n ew p on ds a nd n ur se ri es t he o bs er va nc e o f t he f ol lo wi ng b as icr ul es i s c on si de re d n ec es sa ry t o p re ve nt t he p os si bi li ty o f l os es t hr ou ghdiseases.

1. Each pond must have independent supply and drainage of water i.e.

pond water must not drain into each other, since disease outbreak ino n e p o n d c a n sp r ea d t o o t h er s i n i n t er - de p e nd e n t p o n ds.F a rm e r s m u st

pay particular attention to this for maximum results.

2. In a fish farm having many ponds, special purpose ponds must be

provided for different age group of fish or for different managementpurposes. The dosage treatments for fingerlings in nursery ponds areq ui te d if fe re nt f ro m t ho se o f a du lt f is h i n b re ed in g p on ds . S pe ci al

purpose ponds could include spawning ponds, nursery ponds, feedingponds, breeding ponds and quarantine ponds.

3. The water source to the pond must be suitable, free from pollutants andexclude the entry into the ponds of wild fish and variousd ev e lo p me n ta l s t ag e s o f p a ra s it e s ( c ys t s, e g g s, s p o r es e t c) , w h i ch c a ne xi s t o u ts i de t h e h o st .

20


22/23

6.0 General Hints to FarmersI n s um m ar y, a f i sh f a rm e r ca n p re ve n t or m i n im i ze e co n om i c l o ss e sd u e t o di s ea s e i n fe ct i on s i n fi s h f a rm s b y ta k in g h e ed t o t h e f o ll o wi n g

precautionary measures.

i) Avoid overstocking ponds. Obey stocking rules for d i ff e r en t sp e c i es o f f i sh u n d e r m o n oc u l tu r e , p o l yc u l t ur eand integrated culture.

ii) Ensure good water quality in fish pondsiii) Avoid erratic/irregular feeding practices; starved fish areh i g hl y su sc ep t i b le t o d i se ase s. F e e d f i sh wi t h b a l an c e ddiet.

iv) Prevent access of predators to fishponds. Most predatorsa c t s a s i n t er m e di a t e h o st o f f i sh p a r asi t e

v) Avoid over application of in-organic fertilizer or organicm a n u r e b y f o l l o w i n g r e c o m m e n d e d r a t e s . O v e r f e r t il i z at i o n r e su lt s i n t he r e d uc t i on o f a mo u n t o f d isso l ve do xy ge n i n t he w at er w it h d ra st ic c on se qu en ce s o n f is hhealth.

vi ) S amp le f is h s to ck in po nd reg ul ar ly to mo ni tor fi sh hea lth .S am pl in g a pp li an ce s s ho ul d b e s af e w it ho ut in fl ic ti ngw o un d s o n t h e f i sh .

vii) Isolate and treat or destroy diseased fish to preventspreading of diseases in pond.

vi ii ) I f c at fis h f ing er lin gs a re s to ck ed, s or t t hem t wi ce at tw o

we e ks i n t e rv a l s t o p r e v en t c a n ni b a l ism

I t i s b et te r t o o bs er ve t he se h in ts a nd pr ev en t d is ea se o ut br ea k r at he r t ha ns tr ug gl in g t o c ur e t he m. R em em be r p re ve nt iv e m ea su re s a re b et te r ( le ssexpensive, and more convenient) than curative approaches.

21


23/23

Bibliography

Bolorundu ro, P.I. and A.Y. Abdullahi (199 6). Water Quality Managemen t in

f is h C ul tu re N AE RL S E xt en si on B ul le ti n N o. 9 8 F is he ri es S er ie sNo.3.52p.

Bolorunduro, P.I. (1994). Control of Natural Enemies of Fish. MonthlyTe c h no l o gy Re vi e w M e e t in g s ( M T RM) Tr a i ni n g p ap e r f or ADP S u b j ec t

Matter Specialists. (SMSs) - 4p

Bolorundu ro, P.I. (1996). Prevention and Control of Fish Predators, Parasitesa n d Di s ea s es i n P on d s. M T RM Tr a in i ng p a pe r f or A D P S M Ss . S u bj e ctM a t t er S p e c i al i st s. ( S M S s) - 4 p

Dogiel, V.A, G.K Petrushevski and Yu. I. Polyanski (1970). Eds. Parasitologys to f F is h es 1 E d it i on . Tr a ns l at e d by Z . Ka b at a ( 1 97 0 ) . T. F. H P u bl i ca t io n s,

Inc. Ltd. Hong Kong pp. 265-298.

NIFFR (1996) National Institute for Freshwater Fisheries Research Control of

s om e C om mo n D is ea se s i n F is h P on ds . N IF FR E xt en si on L ea fl etNo.45p.

s tR o be r ts R . J . ( 1 07 8 ) e d. F i sh P a th o lo g y. 1 E di t io n . B a il l ie r e Ti n da l lP u b l ish e r s 3 1 8 p.

Va n Du i j n.C ( 1 9 73 ) Di se ase s o f Fi sh . T h i r d E d i t io n I l l i ff e Bo o k s L t d . L o n do n372p.

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