Observations of Fry Cannibalism in Clarias gariepinus(Burchell, 1822)

Abstract

Fry cannibalism was investigated in Clarias gariepinus with a view of understanding the underlying embryological and early larval life factors responsible for the behaviour. A total of 5.6% of the fertilized egg attained 2-cell cleavage stage than others and 2.3% of the eggs hatched within the first one hour of onset of hatching. About 80% of fertilized egg hatched between 4 and 5 hours after onset of hatching, indicating that 2.3% of hatchlings are more advanced in growth than the rest. Larval survival was highest (70.6%) among the eggs that hatched at 5 hours after onset of hatching and the least was in the eggs that hatched at 6 hours after onset of hatching. The ‘medium jumper' attained the highest weight gain per day (0.056 g / day) while the large jumper recorded the least weight gain per day (0.043 g/day). The ‘small jumper' recorded the highest specific growth rate (2.46% /day) while the least was the ‘large jumper' (1.55% /day). ‘Tail first ‘ cannibalistic behaviour was exhibited by one week old fry while ‘head first' cannibalistic behaviour was recorded in 4-week old post-fry.


Journal of Aquatic Sciences Volume 16, April 2001, pp. 1-6



KEY WORDS:

Cannibalism, Clarias gariepinus, Growth