Unpredictable feeding patterns modulate the growth rate, haematological and behavioural responses of Clarias gariepinus

Abstract

Unpredictability in the supply of fish feed is an understudied welfare issue in the aquaculture sector that could alter the performance and health of farmed fish species. This study examined the effect of unpredictable feed supply on ninety African catfish ( Clarias gariepinus, 10.65±0.11g) under culture conditions for 8 weeks. The fish were exposed to a predictable feeding time (control, T1), early unpredictable feeding time (T2), and late unpredictable feeding time (T3) in triplicates. Growth indices (mean weight gain (MWG), feed conversion ratio (FCR), and specific growth rate (SGR)) were assessed, haematological (PCV, HGB, RBC, WBC, HCT, MCV, MCH, MCHC) and glucose responses were also observed during the study period. Behavioural traits (feeding intake (FI), latency to feed (LF), feed anticipatory behaviour (FAB), aggression rate (AR) and shelter use (SU)) were observed weekly. Statistical analyses were performed using linear models in R (v 4.2.1) package. The unpredictability in feed supply affected (p≤0.05) the growth indices of C. gariepinus with similar (p≥0.05) MWG in T2 and T3. Treatment affected (p<0.05) the FCR, and SGR was highest in fish species exposed to T1. C. gariepinus exposed to T1 had the best condition factor (1.01±0.06) and highest (p≤0.05) survival rate (96.7±5.35). Moreover, WBC, MCH, and MCHC of the fish species were significantly (p<0.05) different between treatments and the glucose response increased (p≤0.05) with treatments. Furthermore, the least FI and highest LF was in T2. FAB was similar (p=0.56) in T2 and T3 while fish in T3 were most (p =0.05) aggressive. Unpredictability in feed supply influenced (p=0.01) the SU of C. gariepinus with similar (p=0.44) SU in T2 and T3. Conclusively, this study provides insight into the growth, haematological and behavioural responses of C. gariepinus exposed to unpredictable feed supply and its implication on sustainable aquaculture production.