Summary of data collected during field efficacy trials of florfenicol and oxytetracycline dihydrate in controlling mortality in walleye (Sander vitreus) because of motile Aeromonad infections

Motile Aeromonad septicemia is a substantial concern during fish propagation and can be catastrophic for fish hatcheries. We tested the efficacy of two different drugs (florfenicol and oxytetracycline) offered with feed as possible treatment options to control mortality because of motile Aeromonad infection. We offered top-coated medicated feeds to hatchery-reared Sander vitreus (walleye) that were naturally infected with motile Aeromonad infection during two separate trials in 2011 and 2012. Substantial walleye mortality occurred before positive clinical outcomes from the medicated feed treatments were observed, and additional treatment measures were taken by hatchery staff to mitigate further mortality in their walleye production tanks. This report summarizes the data that were collected during medicated feed trials. Statistical inferences on treatment efficacy are not included because of the confounding treatments and possible secondary pathogens present throughout this study.