Evaluation of Hydrogen Peroxide and Temperature to Control Mortality Caused by Saprolegniasis and to Increase Hatching Success of Largemouth Bass Eggs

Abstract

We evaluated the use of hydrogen peroxide (H₂O₂), temperature, or both, to control mortality presumptively caused by fungus Saprolegnia in Florida largemouth bass Micropterus salmoides floridanus eggs in a flow-through hatchery system. Four treatments—ambient water (AW; control), ambient water and H₂O₂ (AWHP), heated water (HW), and both heated water and H₂O₂ (HWHP)—were tested on each of 30 replicate spawns. Four 8 cm × 5 cm sections of spawning mat, one for each treatment, were cut from each of the 30 selected spawns. Egg counts on each cut mat section were recorded. Water temperature in all AW and HW trial tanks ranged from 17.9°C to 19.2°C and from 22.1°C to 23.6°C, respectively, during treatment. The water temperature difference between treatments averaged 4.4°C. Hydrogen peroxide trial tanks received two, 100 mg/L H₂O₂ treatments 8 h apart, until hatch. The 7.5 L/min incoming water flow was not reduced during treatment. The addition of HW, H₂O₂, or both, significantly increased mean percent hatch (79, 79, and 91%, respectively) over that of the untreated controls (49%). Significant differences were found in mean percent hatch levels between AW and the other three treatment groups (P < 0.05). The combination of higher incubation temperature and H₂O₂ administration also resulted in significantly greater hatch than did either higher incubation temperature or increased H₂O₂ administration alone; percent hatch did not differ significantly between eggs that either were only incubated at the higher temperature or received only H₂O₂ administration. Increasing incubation water temperature to 22–23°C instead of using only water at ambient temperature (18–19°C) or adding 100 mg/L H₂O₂ twice daily in a flow-through system significantly increased hatching percentage of Florida largemouth bass eggs.

Received May 3, 2011; accepted March 11, 2012

ACKNOWLEDGMENTS

We thank Rick Stout and the Florida Bass Conservation Center staff for their assistance with mat collection. We also thank Bill Pouder and Jon Fury for their comments on this manuscript. We also acknowledge Dr. Jesse Trushenski for her insightful review of this manuscript. Finally, we thank Mark Gaikowski for his help with data analysis.