Food restriction and re-feeding regime can be used as a management tool to reduce feeding cost. The present study was carried out to investigate behavioral adaptation of Nile tilapia to food restriction regime. Fish (n=40) were classified into two groups (n=20/group, 2 replicates). Experimental period was divided into two parts. The first part lasted for 8 weeks while the second part was fulfilled to 11th weeks. The first group (control) fed daily throughout experimental periods. The second group (restricted), fish were restricted of food two days per week during the first part, and then re-fed as control in the second part. Behavior of fish, body weight, body dimensions and water quality were recorded. Weight gain, relative growth rate and feed conversion ratio were calculated. The results demonstrated that food restriction significantly increased resting, schooling and chafing behaviors, but decreased eliminative, chasing and mouth pushing behaviors. Food restriction significantly reduced body weight. However, the relative growth rate and feed conversion ratio were improved in restricted fish than control one. Water quality parameters were improved with increased dissolved oxygen and maintenance pH in restricted fish. It was concluded that Tilapia were adapted behaviorally to food restriction regime by increasing comfort behavior and reducing aggressive behavior that indicate adjustment capability of Tilapia to food deprivation.
Key words: Nile tilapia, food restriction, behavior, adaptation, water quality