Nitrite Toxicity to the Razorback Sucker, Xyrauchen texanus, and the Bonytail, Gila elegans: Inhibition by Environmental Chloride

摘要

Aquaculture for the purpose of supplementing natural recruitment is one approach used to assist the recovery of endangered fish populations. A common consequence of high-density culture is the accumulation of nitrite in the water. Razorback suckers (Catastomidac; Xyrauchen texanuts) survived a 72-hour exposure to 25 mg/L nitrite-N. Bonytails (Cyprinidae; Gila elegans) died within 48 hours of exposure to 10 mg/L and 25 mg/L nitrite-N. A chloride:nitrite ratio of >= 5 (as either calcium chloride or sodium chloride) protected bonytail from nitrite tox-icity. This study provides some basic knowledge that can be applied to the culture of these two endangered species and raises some interesting questions about the nature of nitrite toxicity and inhibitionof toxicity in these two species.