POPULATION DENSITY EFFECTS ON THE BEHAVIOR AND FEEDING OF YOUNG STRIPED MULLET (Mugil cephalus) IN 37.8‐LITER AQUARIA

ABSTRACT The swimming and feeding behavior of striped mullet (Mugil cephalus), 40–60 mm SL, was observed in 37.8‐liter aquaria. Five of the most frequently observed behavioral acts were then chosen as representatives of “normally” occurring behavior under these experimental conditions. These behavioral acts were subsequently counted in the 37.8‐liter aquaria with population densities of 3, 6, 18, 30 and 60 mullet per aquaria, during swimming and feeding observations. More food bites were taken at densities of 18 and 30 than at the other densities. Mullet kept at a density of 30 per tank exhibited the lowest mean number of long traverses (a distance of more than one‐half the aquarium front). Perhaps at a density of 30 mullet per aquarium (0.79 mullet/liter or 231 mullet/m2), food was assimilated into biomass and less was burned for energy. Obtaining data in aquaria in this manner may prove an invaluable tool since it is less expensive than stocking ponds experimentally and can provide a useful basis for deciding efficient stocking densities for any size fish.