Role of vitamin E in growth of an Indian major carp, Catla (Catla catla)

A feeding trial was conducted to study the role of vitamin E in growth of Catla catla fry. Newly hatched larvae of Catla were fed with synthetic diet, supplemented with graded levels of vitamin E α0, 50, 100, 150, 200, 250 mg/Kg of diet. The spawn were fed with five times of their body weight for 30 days. Observation was made on the basis of survival, growth, daily weight gain and food conversion ratio. The significant weight gain and highest survival could be achieved by the diet supplemented with 150 mg of vitamin E per kg of the diet. The weight gain per day in 0, 50, 100, 150, 200 and 250 mg vitamin F/kg supplemented diet were 4.0, 5.2, 6.5, 7.8, 6.8 and 6.3 mg, while survival was 50, 51.8, 52.4, 52.8, 52.2 and 52% respectively.

Status of the beach seine fishery in the Hambantota District during 1995-97

Beach seine fishery is one of the oldest fishing methods practiced in Sri Lanka. In the recent past several modifications were observed in the structure of the net and the material used in the construction of nets. beach seine nets made of nylon material were also reported at 4 operating sites out of 17-beach seine landing centers in the Hambantota District. However, traditional beach seine nets made of coir and kuralon were the common nets used in the area. Fishing season extends from September to April of the following year. However, beach seining at Mawella was carried out throughout the year. The estimated average annual effort for the entire study area was about 4250 operations. The mean annual catch rate at Mawella, Kalametiya and Welipatanwila were estimated as 81.8, 290.7, and 167.3 kg/operation respectively. The mean annual catch rate for the entire study area was estimated as 157.3 kg/operation. The beach seines recorded an estimated annual production of 662mt in the Hambantota district. Stoleophorous sp. has made the major contribution to the beach seine catches and it was about 31.7% of the total beach seine production. Leiognathus sp. Carangids and Trichuras sp. have produced 11.5%, 9.5% and 8.5% respectively while Amblygaster sirm and other Sardinella sp. have produced 5.5% and 4.9% respectively. A sirm was found during the months of November, February, March and July. The size range of A. sirm caught by beach seine during February –March period was in the range of 5-12cm (total length). Contribution by Rastrelliger sp. and Sphyreana sp. were 2.9% and 2.6% by each category. Average income of a beach seine operation at Mawella, Kalametiya and Welipatanwila were Rs. 3330/=, 10250/= and 6222/= per operation respectively.

Influence of stocking density on the culture potential of freshwater catfish Pangasius pangasius in pond

Influence of stocking density on the production of freshwater catfish Pangasius pangasius with formulated feed in ponds was studied. The fish fry were collected from the Meghna river near Chandpur which is a natural breeding ground of this fish. Three stocking densities chosen during this experiment were 5000, 8000 and 11000 fry/ha with an initial weight of 42.57 ±2.51 g. The formulated feed was prepared in the laboratory which contained 45% fish meal, 30% mustard oil cake, 15% wheat bran and 10% rice bran to supply 40.48% protein in feed. The growth of P. pangasius in terms of net weight gain was 409.49, 266.49 and 236.37 g at the 5000/ha, 8000/ha and 11000/ha stocking densities respectively, which was statistically significant (p<0.05). High food conversion ratio (FCR) was also observed during this research study which ranged between 7.06 to 7.72. A production of 2.6 tons/ha at the stocking density of 11000/ha; 2.13 tons/ha at the stocking density of 8000/ha and 2.04 tons/ha at the stocking density of 5000/ha was obtained, while the growth of individual fish at the end of experiment was in opposite order. The result of this experiment indicates that stocking density has significant influence on the culture potential of freshwater catfish P.pangasius.