First report of food and feeding habits of Gangetic ailia, Ailia coila (Hamilton, 1822) from the Ganga River at Prayagraj, India

The present study was carried out to explore the food and feeding behaviours of the commercially significant silurid fish, Gangetic ailia (Ailia coila), in the Ganga River at Allahabad, India. A total of 806 specimens were gathered using gill, cast, and drag nets with different mesh sizes between January and December 2025. Eighty-eight specimens were selected from the collected samples for comprehensive stomach-content analysis to establish feeding habits and trophic ecology. Examination of stomach fullness indicated variation in feeding intensity, 13% trace, 10% full, 12% half-full, 4% one-third full, 6% one-fourth full, 2% nearly half-filled, and 19% empty stomachs. Qualitative and quantitative analyses of stomach contents reveal that the feeding habits of A. coila are mainly carnivorous, especially insectivorous. Aquatic insects were the most important food item, comprising ca. 90–95% of the total gut contents, while caddisflies were the most abundant component. Other essential feeding items included insect parts (thorax, legs, antennae, wings, eyes), chironomid larvae, worms, organic waste, wasp insects, protomatrix and undigested materials. Phytoplankton and zooplankton were present only in trace amounts, suggesting that they were ingested incidentally rather than specifically selected. The relative gut length (RGL) was consistently less than 1, further supporting the species' carnivorous eating pattern. The gut content composition suggested that A. coila mostly forages in the benthopelagic zone, taking advantage of food supplies of both mid-water and near-bottom habitats. The results provide essential baseline data on the trophic ecology of A. coila and contribute to the formulation of effective fisheries management, conservation strategies, and sustainable utilisation of this commercially important species in the Ganga River environment.