Growth and Survival of First Feeding Larvae of<i> Clarias gariepinus</i> Fed Live and Preserved Zooplankton

Abstract

The study was designed to evaluate the growth performance and survival of Clarias gariepinus larvae fed live Zooplankton (LZ), Frozen Zooplnakton (FZ), Dried Zooplankton (DZ) and a mixture of Live and Frozen Zooplankton (LFZ) as well as Live and Dried zooplankton (LDZ). The experiments were conducted in plastic baths of 10 L capacity filled to 5 L mark with dechlorinated domestic water supply (tap). Every bath was stocked with 30 first feeding larvae (3 days old) weighing 12.25 mg – 12.70 mg and randomly assigned the feeding treatments in triplicate. The larvae were fed to satiation twice daily between 09.00 – 10.00 and 15.00 – 16.00 hours. The length and weight of the larvae under the various treatments were measured prior to stocking and weekly for a period of 4 weeks. Also monitored in like manner were pH, temperature and dissolved oxygen content of the culture medium. The percentage survival rate of the larvae were determined per treatment at the end of the feeding trial. The average daily length increase of 0.38 mm, 0.36 mm and 0.35 mm by fish fed LZ, DZ and LDZ respectively are not significantly different (P >0.05) from one another but were however significantly higher (P<0.05) than the 0.29 mm and 0.27 mm length increase by larvae fed FZ and LFZ respectively. The percentage increase in length by all the fish followed the same pattern above within a range of 55 – 63.63%. The average daily weight gain of 9.0mg by larvae fed on LZ is significantly higher (P < 0.05) than the weight gains on the rest feed treatments which were however not significantly different from one another. While the specific growth rate followed the same pattern as weight gain, the percentage weight gain in the range of 94.17% - 95.30% did not vary significantly (P > 0.05) with the treatments. The larval survival rates which was similar for FZ, LZ, and LFZ were within the range of 65.56% - 68.89%. This is followed by the survival rate of 56% by larvae fed DZ. It was concluded therefore that preserved zooplankton was suitable for the rearing of Clarias gariepinus larvae with the frozen zooplankton giving a better rate of larval survival. The strategy for using preserved zooplankton in larval rearing is also advanced.



Journal of Aquatic Sciences Volume 16, April 2001, pp. 29-32



KEY WORDS:

Zooplankton preservation, Clarias larval growth and survival