ARS | Publication request: Feeding Aquaflor® medicated feed to sunshine bass at up to 5 times the recommended dose

Submitted to: Annual Drug Approval Coodination Workshop
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2010
Publication Date: August 3, 2010
Citation: Straus, D.L., Bowker, J., Bowman, M., Carty, D., Mitchell, A.J., Farmer, B.D. 2010. Feeding Aquaflor® medicated feed to sunshine bass at up to 5 times the recommended dose [abstract]. Annual Drug Approval Coodination Workshop. 16:89-94.

Technical Abstract: Aquaflor® (florfenicol) is approved for use in catfish for Enteric Septicemia of Catfish (ESC) and conditionally for columnaris, and in Salmonids for furunculosis and coldwater disease. It has reached wide acceptance as a safe and effective therapeutant for its approved indications, but there is an interest to increase the recommended dose rate. This presentation demonstrates its histological safety to sunshine bass when fed at the therapeutic rate of 15 mg florfenicol/kg body weight/day, and at 3 and 5 times this rate, for 20 days (2 times the normal treatment period). Sunshine bass (average = 13.7 g) were randomly stocked into 15 tanks (20 fish/tank). There were four replications of each treatment including the control, with three surrogate tanks. The surrogate tanks were used to calculate the proper feeding rate. Tanks contained 100 L of flow-through well water. Water temperature and dissolved oxygen were measured daily and pH, alkalinity and hardness levels were recorded at the beginning and end of the study. The medicated feed was top-coated with Aquaflor® and fed at 2% body weight/day; feed was offered in the morning and afternoon. After the acclimation period, fish were fed their respective diets for 20 consecutive days. Fish were monitored for feeding activity, mortality, and morbidity. There were no mortalities and fish ate all feed offered (usually within 10 seconds). At the end of the study, fish (except surrogate fish) were euthanized, necropsied and examined by histopathology. There were no dose-related effects on behavior, feeding, growth or lesions in histological samples. Therefore, the Safety of Aquaflor® to sunshine bass is at least 75 mg florfenicol/kg body weight/day when administered for 20 consecutive days.