Diet composition and its relation to the characteristics of the digestive tract of the blue sea catfish, Ariopsis guatemalensis (Actinopterygii: Ariidae), in Barra de Navidad Lagoon, Jalisco, Mexico

Abstract

Diet composition and the characteristics of the digestive tract of the blue sea catfish, Ariopsis guatemalensis, in a coastal lagoon in western Mexico were investigated. This species is consumed by locals and it has been used as a bioindicator of sewage pollution. This study aimed to determine if the feeding habits of this species were related to the macroscopic and microscopic morphological characteristics of the digestive tract. Specimens were captured in the Barra de Navidad Lagoon (Jalisco, Mexico) from 2011 to 2016. For every fish collected, total length (TL) was recorded and the esophagus, stomach, and intestine were extracted for histological analyses and identification of food items in their diet. The macroscopic and microscopic characteristics of the digestive tract and the stomach content analysis indicate A. guatemalensis is a carnivorous species with preference for goby fish. Crustaceans were the second most important food item and were dominated by portunid crabs and mud shrimps. The size and position of the mouth, the presence of dental plates on the vomer, palatines, premaxilla, and pharynx, and the presence of goblet cells in the digestive tract are characteristic of fishes that consume live hard-bodied prey and crush their food before it enters the esophagus. The relatively short intestine and the folds in the mucous membrane are characteristic of carnivorous fishes.