Feeding habits and digestive enzymes in the gut of Mormyrus rume (Valenciennes 1846) (Osteichthyes Mormyridae)

摘要

The feeding habits of 436 elephant snout fish, Mormyrus rume (Valenciennes 1846), from River Ose were investigated. Stomach contents were identified and analyzed by occurrence and volumetric methods, and the prominence of individual food items was determined by the ranking index I. Only 3.2% of the specimens had empty stomachs while the others had stomachs in varying degrees of fullness. Food items included plant and animal matter, mainly arthropods. A preponderance of insects, crustaceans and detritus, which accounted for 100% occurrence and > 16% of total volume in the stomachs of M. rume specimens, suggests a benthic feeding habit. The high percentage occurrence of detritus and its high I value established M rume as a detritivore. Assays were conducted to determine the occurrence, distribution and specific activities of digestive enzymes in different gut regions of juvenile (SL < 35.0 cm) and adult (SL > 35.0 cm) M. rume. Alpha-amylase, maltase, lactase, sucrase, chitinase, pepsin, trypsin and lipase were present in the different gut regions at varying quantities and with specific activities. The wide distribution of enzymes in both juvenile and adult M. rume reflects its ability to digest the carbohydrate, protein and lipid portions of its foods. There were no differences (P > 0.05) in specific activities of digestive enzymes between wet and dry seasons.