Comparison of the feeding behaviour and strategy of the Killifish, Aphanius sophiae Heckel, 1847, at two different localities in Iran

Abstract

The feeding strategy and behavioural differences of a Killifish, Aphanius sophiae Heckel, 1847, were compared at a freshwater spring (Cheshme-Ali at Damghan) and a salty water river (Shour River) by considering stable and non-stable environmental conditions. The results showed that Killifish were affected by environmental differences. Chironomid larvae were its main food item in Shour River, whilst the species mainly fed on crustaceans and Daphnia at Cheshme-Ali. In Cheshme-Ali, the fish had suitable feeding for almost the whole year in spite of some fluctuations during the period of shortened daylight. In Shour River, however, the case was affected by salinity and thermo period. Therefore suitable and stable conditions allowed more prey selection for Killifish in Cheshme-Ali than in Shour River. The observations demonstrated that Killifish probably preferred to hunt a specific prey that is abundant and easy to capture. Furthermore, the size of both prey and predator can affect their feeding diversity. The results in Shour River showed a higher relative length of gut (RLG) (p<0.05) which means more energy utilization and osmoregulation in the gut. Also the Shour River population shows a relatively benthic, passive behaviour and a low condition factor (p<0.05) that is caused by different and non-stable conditions.