Behavioral Characteristics of Largefin Longbarbel Catfish Hemibagrus macropterus: Effects of Sex and Body Size on Aggression and Shelter Selection

Abstract

This study explored the aggressive behavior of Hemibagrus macropterus (Bleeker, 1870), a commercially valuable fish, to understand how size, sex, and shelter availability influence their interactions. By observing fish of different size combinations (large vs. large, large vs. small, small vs. small), sex combinations (male vs. male, male vs. female, female vs. female), and shelter types (tiles, pebbles, grass) under varying group densities (1, 3, and 6 fish), we found that H. macropterus is more active and aggressive at night, establishing a social hierarchy with dominant and subordinate individuals. Larger fish and females showed higher aggression, but the presence of shelters, especially tiles and pebbles, significantly reduced aggressive interactions. Fish preferred tile and pebble shelters, with no cohabitation in these, while aquatic plants allowed two fish to share space. Aggression was higher in larger groups, suggesting that managing group size and providing adequate shelters can reduce conflicts. These findings highlight the importance of nocturnal feeding, size-segregated rearing, and sufficient shelters in aquaculture to minimize aggression, improve fish welfare, and enhance cultivation efficiency. This research provides practical insights for optimizing the culture of H. macropterus and contributes to understanding the behavior of similar fish species.