Gut contents of silver carp — Hypophthalmichthys molitrix (Val.) — and some trophic relations to other fish species in a polyculture system

This work is a continuation of the studies conducted in the ponds of the Fish and Aquaculture Research Station, Dor, in 1975 concerning the components of fish feed under conditions of polyculture, with additional food and intensive fertilization.A study was made of the food eaten by the silver carp, Hypophthalmichthys molitrix (Val.), grown with or without supplementary food in ponds that had previously been used for storage of fish fed on pellets (ponds Types 1 and 3), or which had been kept dry for various periods of time (ponds Types 2 and 4).The special pattern of its gills, which are adapted to retain suspended organisms and particles of sizes less than 20 μm, enables the silver carp to filter enormous quantities of phytoplankton and organic particles.A comparative study was made of the trophic relations existing between Hypophthalmichthys molitrix (Val.), Cyprinus carpio (L.) and Tilapia aurea Steindachner, which were the principal species in the polyculture system, and of the influence of the type of pond used on the growth of the fish.