Water quality in a closed recirculating fish culture system influenced by addition of a carbon source in relation to feed uptake by fish

Abstract

. In a closed recirculating fish culture system with a rotating disc filter serving as ‘biofilter”, waterquality was maintained by the addition of hydrolysed corn starch in the settable solids tank. According to the feed uptake by rainbow trout. Salmo gairdneri Richardson, starch was introduced to adjust a nutrient relation of organic C:N of 1·6:1 for the bacterial biomass. Trout grew from 42 g to 254 g in body weight in 118 days. No differences in feed uptake and feed conversion rate were observed in a control group held in a flow-through system with tap water as culture medium.