An evaluation of the Cascadu, Hoplosternum littorale (Hancock, 1828) as a candidate for aquaculture
1992
Ramnarine, I.
Several aspects of the biology of the cascadu were examined in an effort to evaluate the fish as a candidate for culture. A hatchery technology based on the use of brine shrimp nauplii as a live food was developed. It was found that after a period of 61 days, the juveniles weighed 1.8g +- 0.3g and measured 41.8mm +- 3.2mm. The survival rate was 84 %. There were two critical stages in larval rearing. The optimum dietary protein requirement was determined experimentally was found to be 35 % at 26 degrees celsius. This suggests that the cascadu is an omnivore rather than a detritivore as previously reported. A commercial ration of assay 35 % crude protein was formulated and manufactured and a field trial was conducted in a 0.8-ha earthen pond employing 12,000 hatchery-reared juveniles. After a grow-out period of 28 weeks, the fish were harvested. The mean weight was 67.2 g and the percent survival was 45. The high mortality rate possibly resulted from predation of the juveniles by aquatic insects, mainly dragonfly larvae. The high feed conversion ratio of 3.38:1 is a direct result of the high mortality rate. It is suggested that the nursery phase is very important in the culture of the cascadu. The study has shown that the culture of the cascadu is technically feasible. Concludes that although the cost of production is high, averaging about $13 per kg, cascadu culture is economically viable since the fish fetches a price of up to $40 per kg.
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