Characteristics of Filter Feeding Organs and Digestive Tissues, and Feeding Strategies of Hypophthalmichthys molitrix and Aristichys nobilis

Purpose To study the characteristic differences of plankton uptake, self-feeding organs and digestive tissues between Hypophthalmichthys molitrix and Aristichys nobilis, and to analysis the correlation between different bait selection and feeding organs structure and digestive tissues of H. molitrix and A. nobilis.

Methods H. molitrix and A. nobilis of Yunlong Reservoir were collected and the gill rakers were extracted for morphological observation and measurable data analysis. Tissue sections of H. molitrix and A. nobilis foregut were prepared to analyze the tissue differences. The intestinal contents of H. molitrix and A. nobilis were extracted to analyze the bait composition.

Results The gill rakers of H. molitrix were longer than the gill filaments, gill rakers connected to each other, fusion and long, like a comb, the gill membrane was covered on the outside of the gill raker, forming a sieve plate, the inside of the gill had a spongy gill silk mesh, the whole gill rakers liked spongy. The gill rakers of A. nobilis were dense without the gill filament mesh, the gill rakers were slightly shorter than the gill filament, and each gill arch had two rows of symmetrical gill rakers. Both the foregut tissues of H. molitrix and A. nobilis were composed of mucosal layer, submucosal layer, muscle layer and serosa layer. The muscle layer of H. molitrix was thicker than the muscle layer of A. nobilis. A total of seven zooplankton species were found in the intestinal contents of H. molitrix and A. nobilis, with an overlap rate of 57.14%, and A. nobilis fed more on zooplankton than H. molitrix. There were 44 species of phytoplankton in the intestinal contents of H. molitrix and A. nobilis, 38 species were ingested by H. molitrix and 31 species were ingested by A. nobilis. 25 species of phytoplankton were both ingested by H. molitrix and A. nobilis, with an overlap rate of 56.82%. H. molitrix and A. nobilis fed on both zooplankton and phytoplankton, H. molitrix mainly fed on phytoplankton, and A. nobilis mainly fed on zooplankton.

Conclusion The structure of filter-feeding organs and digestive tissue plays an important role in determining the feeding strategy of H. molitrix and A. nobilis.