HATCHING SUCCESS OF Clarias gariepinus EGG USING DIFFERENT INCUBATING SUBSTRATES AND VARYING EGG AREA DENSITY

Abstract

This study evaluated the efficiency of different substrates and best egg area density for hatching Clarias gariepinus
egg. The different substrates used were Polyvinyl chloride (PVC) frame with fine mesh (1 mm x 1mm) net, fine mesh
net, sack thread and the control was without a substrate. Result obtained shows that eggs hatched on PVC frame
with fine mesh net and ordinary fine mesh net had higher hatchability (79.40% and 77.55% respectively) compared
to eggs hatched on sack (64.75%) and the control bowl without a substrate (20.70%). However, screening efficiency
of un-hatched eggs from the hatched eggs were better using PVC frame with fine mesh net compared to other forms
of substrate used. Based on the efficacy of PVC frame with fine mesh net substrate, this substrate was then used for
the next study which was designed to determine the best area density for optimum hatching; increasing egg-mesh
ratio (estimated in gcm-2 i.e. mass of egg to the mesh area) namely, 0.58, 1.16, 1.74, 2.31, 2.85, 3.47,4.05, 4.64 and
5.52 was used for this study.The result revealed that beyond 4.05 area density, hatchability was significantly
reduced (below 50%). Hence, for higher hatching success of African catfi