Diet composition and feeding habits of flat needlefish Ablennes hians (Valenciennes, 1846) (Beloniformes: Belonidae) in the Southeastern Arabian Sea

The study describes the feeding habits, diet composition and prey diversity of Ablennes hians based on 396 specimens collected between October 2015 and September 2017 from Kerala, south-west coast of India. The Index of Relative Importance (IRI) showed that teleosts were the most preferred food items (%IRI = 65.43 %) followed by molluscs (%IRI = 32.91) and crustaceans (%IRI = 1.66). Prey biodiversity analyses indicated no significant variation in the prey items between the sexes and immature (juvenile) and mature (adult) specimens. Similarly, a non-significant difference in Vacuity Index (VI) and Fullness Index (FI) was observed between the sexes (p > 0.05), juveniles, and adults (p > 0.05). Mean number of prey items per stomach (Nm/ST) was found to be higher in females and juveniles than males and adults; whereas the mean weight of prey items per stomach (Wm/ST) was higher in females and adults. Analysis of similarities (ANOSIM) test also indicated that there was no significant difference in prey types and preferences between sexes (global R = -0.25, P > 0.05) and juveniles and adults (global R = 0.5, P > 0.05). Diet analysis revealed that the species is a carnivorous and active pelagic predator, predominately consuming teleost fishes and an opportunistic feeder and might perform vertical migrations in search of food. The present study provides a first reference on the detailed information on feeding biology of the flat needlefish, which can be used as a baseline information for future studies in the region.