Nutri-toxicological effects of dietary cyanobacteria and the recovery after exposure were investigated in different fishes including yellow catfish (Pelteobagrus fulvidraco Richardson), hybrid tilapia (Oreochromis niloticus × O. aureus) and hybrid sturgeon (Acipenser baeri Brandt × Acipenser gueldenstaedtii).
Three growth trials were conducted to evaluate the nutritional and toxicalogical effects of dietary inclusion of cyanobacteria and the recovery ability of fishes after dietary cyanobacteria exposure (fish were fed the diet without cyanobacteria). Growth and feed utilization (feeding rate, specific growth, feed conversion efficiency, nutrient retention, apparent digestiblity) and hepato-pathological changes and accumulation of microcystins (MCs) in fish tissues (liver, kidney, whole intestine and muscle) were determined. After a period of recovery, the above parameters were used to evaluate the recovery response of fishes after the exposure. Another growth trial was conducted to investigate the effect of dietary inclusion of glutathione (GSH) on the toxicological impact of cyanobacteria on yellow catfish.
Dietary cyanobacteria could result in different nutri-toxicological effects on yellow catfish, hybrid tilapia or hybrid sturgeon. After the recovery, the fish previously fed low or medium cyanobacteria diet could be completely recovered. The fish previously fed high cyanobacteria diet showed an apparent alleviation and might require longer time for complete recovery. Optimal dietary GSH inclusion could help to reduce the toxic effect of dietary cyanobacteria while high GSH could be toxic to fish.