Growth response and survival of Heterobranchus longifilis cultured at different water levels in outdoor concrete tank
Journal Title: Aquaculture, Aquarium, Conservation & Legislation - International Journal of the Bioflux Society - Year 2011, Vol 4, Issue 3
Abstract
Thirteen-day-old hatchery-raised fry obtained from hormonally-induced spawns of mature African catfish H. longifilis broodstock were introduced to three different water levels (0.35, 0.50 and 0.65 m) in four replicates in 12 units of 2x2x1m[sup]3[/sup]outdoor concrete tanks. The fry were similarly stocked initially at 50 fry m-2and later thinned down to 5 fish m[sup]-2 [/sup]and cultured for 6 months. Fish were fed twice daily with commercial pellet feeds (Coppens™) while adjusting the feeding rate from 10 to 4% body weight and pellet size from 0.2 to 4.5 mm. The effects of pond water levels were evaluated in growth responses and survival. Water quality variables were similar (p > 0.05) in all compartments. Temperature, dissolved oxygen and pH were at the optimum level for fish. The results reveal significant (P < 0.05) treatment effects on growth performances. Fish kept at the highest pond water depth (0.65m) were heavier (P < 0.05) and had a higher specific growth rate (P < 0.001) than the others. Food conversion ratio and survival rate were unaffected by the experimental treatments. ANOVA revealed significant differences (P<0.05) with culture period. The lowest water depth (0.35 m) favored fish growth in the first 3 months while the highest water depth (0.65 m) favored fish growth from the fourth month upwards (P<0.05). These results are important because they indicate the optimum water depths for the culture of H. longifilis from fry to sub-adult and from the grow-out/fattening of sub-adult to adult, respectively, in outdoor concrete tanks.
Authors and Affiliations
Anthony Nlewadim, James Udoh, Aniekan Otoh
Keywords
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