A design has been developed to adopt in freshwater fish seed farms for controlling crabs and snakes. The method is convenient and effective. It prevents the entry of crabs and snakes into the ponds

Sharma, A.K.

Sinha, P.S.R.K.

Sreeramamurty, K.B.

Aquatic Commons

Journal of the Indian Fisheries Association, 
12 & 13~ 1982-83~ 27-29 
CONTROL OF CRABS AND SNAKES IN FRESHW A1ER FISH SEED FARMS 
P.S.R.K. SINHA, A. K. SHARMA AND K. B. SREERAM.AMURTY 
Freshwater Fish Farm, CIFE (!CAR) Balabhadrapuram-533 360, Andfzra Pradesh. 
ABSTRACT 
A design has been developed to adopt in frcshwuter fish seed farms for 
controlling crab:; ·and snakes. The method is convenient and effective. It 
:prevents the entry. of crabs and snakes inlto the ponds. 
Crabs such a,s Scyll.a ,\'erra,ta, Scsarma taenio'lata, etc., and snakes have been 
reported to cause considerable leaks to farm ponds and loss to fish fry and finger·· 
lings in brackishwater farms. Their control measures haNc been suggested by 
earlier workers (Hor'a and Pillay,. 1962 Pillai; 1962: Djujadriredia, 1957; Ling, 
1960) . A few methods have been si.1ggestcd to control the loss bdrtg caused due 
to potamonid crabs and snakes in freshwater. Screens made of split bambool:i 
have been recommended to fix around the breeding and hatching hapas to protect 
ihe 03i!p e.ggs and: spawn from crabs by C:honder· ( 1980·) . A fsw poison& are in 
use tn prevent the entry of potamonids and snakes into the nurseries. Indiscri-
minate use of the poisons in and around the fish fanns may directly kill the spawn, 
fry and even iarge fish. These poisons may also accumulaJt:e. in the pond soil, and 
the use of poisons in the :long run .may rcsp.lt 1n. biomagnifiq.tion. 
Therefore, a design has been aeveloped to adopt in freshwater fish seed 
fanns, and is described in this paper. Adoption of this design does not threaten 
the fish life in the fann . The design is shown in. the transverse vertical cross 
section of a modol pond (Fig. l ) and jn aerial view of a series of model nurse-
ries (Fig. 2) . 
The dr.-sign shows a plastered brick wall around each nursery pond in the fam1. 
The wall' should have a wirl.th of 12. 5 to 25 cltl and a height 0f 60 em abovl.! 
the ground level. Tne top of tliis waH may preferably be with.'fringed Hpg project-
ing on both the sides about 10 em. This waJI. serves as a barrier and physically 
prevents the entry of crabs axH.i snakes from outside. The water inlets and outlets 
are fitted with box:ys, each made of galvanised iron on the. four sides and fine mesh 
(iron) ar: the bottom with top op~n. The length, wjot,n ap.d height of .the box may 
be 2 m, 1m and 1m respectively. Crabs cannot climb the vertical sides of the box 
and do not paS:Il through the fin~ mesh at the bottO'ITl . The box and mesh are to 
be painted ;.ith antirust pa[nt and checked from time to time. The ground on 
both the sides of the barrier wall upto 25 to 30 em is to be made plrun. Growth 
28 SINHA, SHARMA ANP SREERAMAMURTY 
scale 1:100 
Fig . 1 . Transverse vertical cross section of a model pond for prevention of crabs 
and snakes. (bw) Barrier wall, (C) Crest, (d) Depth, (e) Emb~nkment, 
(fb) Freeboard, (gl) Ground level, (pb) Pond bottom, (r) Revetment, (s) 
Slope, and (w) Water. 
scale 1: 500 
np 
t \ 1/ i . IC bw e 
Fig. 2. Aerial view of a series of model nurseries for prevention of crabs, and 
snwk:es . ( ic) Inlet channel, ( np) Nursery pond and the remaining as in the 
first figure. 
of weeds and grass is to be prevented by frequent cutting. The embankments may 
be revetted with stones, Sltone slabs or bricks to protect the bunds and the barrier 
wall. against wearing off df the bund material and to prevent the crabs frontburrow 4 
ing, Such revetted embankments Will not proVide shelter for crabs and snakes'. 
CONTROL OF CRABS AND SNAKES IN SEED FARM 29 
If crabs and snak~s are already existing in the farm ponds before construction 
of the barrier wall, they may be killed by poisoning or manually after drying the 
ponds . The farm ponds will then become free from crabs, and snakes for eve·r, 
if the meshes of the inlets and outlets are maintained carefully. The barrielf' wall 
laiSts for a number of years without any special care. Entry of any cattle should 
be stopped by fencing all around the farm to minimize the maintenance cos,t of 
the barrier wall. However, due to the absence of snakes, the rodent popula,tion 
may increase causing dama1ge to the bunds. These roden:ts may be killed by filling 
the water into the ponds, 15 em over the bund level. 
REFERENCE 
Chonder, S. L. 1980. Hypophysation of Indian major carps. Satish Book Enter-
prise, Moti Katra, Agra-3 (India), 112pp. 
Djajad!Lredja, R. 1957. A preliminary report on the introduction of the Phillipine-
type nursery in Indonesia. Tech. Pap. lndo-Pacif. Fish. Cduncil/C /7 I 17, 
23 pp (Mimeo) . 
Hora, S. L. and Pillay, T. V. R. 1962. Handbook on fish culture in the Indo 
Pacific Region. F.A .0. Fish. Bial. Tech. Pap. 14. 204 pp. 
Ling, S. W. 1960. Control of competetors, predators, disease and paras1tes. 
Lecture presented at the Third International Inland Fisheries Training Centre, 
Bogar, Indonesia, F. A. 0. , Rome, 1 p . 
Pillai, T. G. 1962. Fish farming methods in Phillipines, Indonesia and Hong 
Kong. F.A.O. Fish. Biol. Tech. Pap. (18): 68 p. 


Control of crabs and snakes in freshwater fish seed farms

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Control of crabs and snakes in freshwater fish seed farms

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