Feeding selection in a molluscivorous catfish

[Silurus]

Grudpan, C, P Avakul & U Kovitvadhi, 2016. Feeding selection on mollusk by the Indochinese molluscivorous catfish (Helicophagus leptorhynchus Ng & Kottelat, 2000) in the Mun River, Thailand. Kasetsart University Fisheries Research Bulletin 40: 26–38.

Abstract

The gut contents of the Indochinese molluscivorous catfish, Helicophagus leptorhynchus were investigated. The fish were collected from the Mun River, the largest Mekong tributary in Thailand, between February 2008 and February 2009. Two sampling sites with different geographical characteristics, i.e. Tha Ngoi and Khong Chiam, were selected. The first site has a muddy and sandy bottom and the other site has rapids with deep pools. Food items were dominated by mollusks with some other food types occasionally found. Twenty species of mollusks, both gastropods and bivalves, were observed, namely Corbicula moreletiana, Pachydrobia zilchi reducta, Melanoides tuberculata, Lacunopsis munensis and Limnoperna siamensis. The finding is contrary to previous reports on the feeding habits of H. leptorhynchus which said that this fish species feeds exclusively on bivalves. This study showed that food items were manipulated by space and time as well as life stage of the fish. Results also showed that the larger the fish grows, the bigger the mollusks that are being chosen as food.