Silver (Hypophthalmichthys molitrixVal.) and grass carp (Ctenopharyngodon idella Val.) breedingin a municipal treated wastewater

The possibility of silver (Hypophthalmichthys molitrix Val.) and grass carp (Ctenopharyngodon idella Val.) breeding in a pond of fish culture receiving the HRPTS [High Rate Ponds Technology System] effluent was studied. The experiment was achieved at the wastewater treatment plant of the "Institut Agronomique & Vétérinaire Hassan II" in Rabat (Morroco). No supplementary food was added to the fish pond. During a study period of 100 days, the silver carp production was very important (1.2 kg.m-3), with a low mortality rate (12%). The individual mean weight increased from 13 to 113 g, with a mean weight gain of 1 g.day-1. The grass carp production showed a very low production (0.05 kg.m-3) and a high mortality rate (up to 46%). The individual meanweight changed from 2 to 36 g, with a mean weight gain of 0.34 g.day-1.   Key words: Treated wastewater - Silver carp - Grass carp - Fish production - Morocco