Evaluation of Naturally‐Occurring Organisms as Food for Juvenile Crayfish Procambarus clarkii¹

Nutritionally important food items for crayfish have been difficult to identify and little information exists for third instar (first‐feeding) crayfish. In this study, three major groups of potentially‐important foods were fed to communally‐reared third instar crayfish ( Procambarus clarkii ) and weight gain and survival were measured over a 30 day period. Mean weight gain (% increase) of crayfish fed the zooplankton Daphnia magna alone or in combination with other food items, ranged 2, 277–3, 239%, while mean weight gain of crayfish fed unidentified aquatic bacteria, the aquatic macrophyte Myriophyllum spicatus , combinations of bacteria and plant, or a negative control ranged 254–767%. No significant interaction of food items was detected. Bacteria appear to be a utilizable nutritional source for juvenile crayfish, but, using the methods employed in this study, do not support maximum rates of weight gain. Thus, pond management strategies that maximize zooplankton populations at the time of crayfish hatching might be beneficial.