Toxicity of Hydrogen Peroxide to Fingerling Walleyes

Abstract

The toxicity of hydrogen peroxide (H₂O₂) to fingerling (80-160 mm total length) walleye, Stizostedion vitreum, was evaluated. Walleye were exposed in a 1 hour static bath to 50, 75, 100, 200, 225, 250, 400, and 600 ppm (µL/L) active ingredient (H₂O₂) in five experiments. Three to six replicates of each concentration were used in each experiment, with 25 fish per replicate. After resuming flow, concentrations of H₂O₂ in the tanks declined by 23.8% every hour, reaching 0 ppm (µL/L) about 3.5 hours after treatment. Mortalities, as well as dissolved oxygen, temperature, and H₂O₂ concentrations were monitored at 1, 12, 24, 48, 72, and 96 hours. Dissolved oxygen concentrations increased 0.25-1.16 ppm (µL/L) 1 hour after the addition of H₂O₂, because of the dissociation of H₂O₂ (2H₂O₂→2H₂O + O₂). The LC₅₀ following a single 1-hour exposure ranged from 145.1 ppm (µL/L) at 12 hours to 142.8 ppm (µL/L) at 96 hours, which indicates that the toxic effect is mainly from initial contact. The toxicity threshold for walleye is about 50 ppm (µL/L) (1.3% mortality at 96 hours following 1 hour exposure). Other studies indicate that rainbow trout, Oncorhynchus mykiss, tolerate up to 250 ppm (µL/L) for 1 hour, but fingerling walleye should not be exposed to more than 50 ppm (µL/L) for the same exposure interval.