Feeding habits and the influence of pellet diameter on the feeding responses of the flathead grey mullet (Mugil cephalus) in captivity

Abstract

The feeding habits and effect of the diameter of pelleted feeds on the feeding responses of wild juvenile and adult flathead grey mullet (Mugil cephalus) in captivity were examined. Optimal pellet size for feeding was defined according to the behavioural responses and ingestion of pellets with different diameters (2, 4, 6, 8 mm) that were dropped into the tank in a random sequence. Larger pellets (6 and 8 mm) were more attractive (lower reaction time, high percentage of capture), but the small to medium-sized pellets (2 and 4 mm) were consumed the most. The optimal size was the 2- and 4- mm pellet diameter for juvenile individuals (365.50 {+/-} 36.90 g; 28.8 {+/-} 0.84 cm) and the 4-mm diameter pellet for adults (937.49 {+/-} 146.54 g; 40 {+/-} 1.12 cm). The preferred feeding area of adult mullet was also studied to estimate preference in relation to pellet characteristics such as floating or sink. Two pellet types, floating or sinking, were offered simultaneously in the water column: at the surface, mid-water column and bottom of the tank. The flathead grey mullet had a preference to feed in the mid-water column and the bottom of the tanks indicating that sinking or slow-sinking pellets would be the optimal feed type in relation to mullet feeding behaviour.