Effects of graded activated charcoal in rice husk diets for mud catfish, Clarias gariepinus juveniles (Teleostei: Clariidae)

This study investigated the growth performance, nutrients utilization and haematology of Clarias gariepinus juveniles fed with graded activated charcoal (AC) in rice husk (RH) diet. Eight diets were formulated; Control diet 1 (without RH and AC), Control diet 2 (+AC), Diet 3 (2.5% RH), Diet 4 (2.5% RH+AC), Diet 5 (5.0% RH), Diet 6 (5.0% RH+AC), Diet 7 (7.5% RH), Diet 8 (7.5% RH+AC). Diets were fed to triplicate groups of ten fish per tank thrice daily to satiation for eight weeks. Fish fed Diet 4 recorded highest values for mean weight gain (MWG) (75.71±1.76g), SGR (2.40±0.03%/day) and PER (3.22±0.15) while fish fed Diet 7 had the least values for MWG (59.50±1.21g), SGR (2.09±0.03g) and PER (2.39±0.10). The AFI did not record significant difference (P 0.05) while FCR had significant difference (P 0.05) across diets, with Diet 4 having the best value for FCR (0.86±0.04). Diets of RH lower cholesterol, PCV and Hb levels in the experimental fish though, the inclusion of AC to the test diets resulted in a non-significant increase in the levels of these parameters. The values of WBC and RBC did not show significant differences (P 0.05) amongst diets however, Diets 1 and 2 recorded the highest values for WBC (14500±707.11) and RBC (6.15±0.91) with the least values (9000±2828.43 and 5.15±0.21, respectively) for these parameters recorded with Diets 3 and 7. The improved growth recorded at 2.5% inclusion level of AC suggests that activated charcoal could favourably be added to the feed of C. gariepinus juveniles.