Effect of commercial probiotics on growth performance, carcass quality and haematological profile of Clarias gariepinus (Burchell, 1822) juveniles cultured in concrete tanks

Two thousand (2000) Clarias gariepinus fingerlings (5.25 g) were obtained from a reputable fish farm in Lagos and were transported to the grow-out section of the Aquaculture Department, Nigerian Institute for Oceanography and Marine Research, Badore, Lagos. Four concrete tanks (2 m x 6 m x 1 m) were thoroughly washed with saline water; two of the concrete tanks were used to culture fish without probiotics, while the other two tanks were used to culture fish with the application of probiotics. Each of the tanks was stocked with four hundred (400) juveniles. The experimental fish were fed twice daily (morning and evening) for ten (10) weeks with an appropriate size of the feed, and the size of the feed was later adjusted based on the size of the fish. The data generated on the fish weight fortnightly were used to calculate the growth performance of the fish. At the end of the 10-week experiment, two fish were randomly selected from each treatment and blood samples were taken by caudal puncture into heparinised capillary tubes for selected haematological analyses using standard methods adopted in fish haematology. The proximate (carcass) composition of the experimental fish was also determined. The experimental big fish without probiotics (C2) had the highest mean weight gain, while the experimental small fish (C1) had the least mean weight gain. The growth performance of the experimental fish also revealed that all the fish had a better food conversion rate (FCR) and a high survival rate. The result of the ten-week experimental period of Clarias gariepinus showed that probiotics can be incorporated into the feed and or the culture system without any adverse effect on the haematological profile of the fish, but the use of probiotics did not enhance the growth of the Clarias gariepinus in this study.