Nitrite Toxicity to Southern Flounder Paralichthys lethostigma in Fresh and Brackish Water

As flatfish landings have declined in recent years, interest in culturing native flounder species for food or stock enhancement has increased. The southern flounder Paralichthys lethostigma is an important commercial and recreational species, and efforts are currently underway to develop mass culture techniques. Nitrite may reach detrimental concentrations for many fishes in pond and recirculating aquaculture systems. Exposure to nitrite can affect growth and increase mortality in fish. Most studies have evaluated the effects of nitrite on freshwater teleosts because nitrite is generally more toxic to freshwater species than to marine species. Because southern flounder are euryhaline, the potential for culture in both freshwater and saltwater environments exists. Therefore there is a need to determine the toxicity of nitrite in both fresh and brackish water. The objectives of this study were to determine the relationship between environmental and plasma nitrite concentrations for this species in fresh and brackish water (nominally, 1 ppt synthetic sea salt) and to relate plasma nitrite concentrations in exposed fish to mortality.