TECHNIQUES FOR REARING MARGINED MADTOM FRY

The margined madtom Noturus insignis was used as a model species to de velop methods for rearing madtoms in the laboratory. Commercial flake food, salmon starter, Larval AP100, Kyowa Fry Feed, and brine shrimp A rtemia sp. were tested as diets. In rearing trials, mean growth rates of fry ranged from 0.17 to 0.58 mm/d, and the fastest growth rates wer e obtained with brine shrimp as part or all of the diet; however, the highest survival was obtained with a diet of salmon starter. Approxima tely half of the total fry mortality occurred within the first 2 d in feeding trials, and mortality after 5 d was low. Tanks apparently need to be thoroughly cleaned twice daily to ensure good survival of larva e and fry. The rearing system used in this study and a stocking densit y of only one fish per 2 L of water precluded large die-offs, even whe n parts of the system failed. Twice-daily feedings of 300-400 mg of sa lmon starter per 38-L tank, supplemented with about five brine shrimp nauplii per milliliter, are recommended for rearing madtom larvae to 2 -3 weeks of age. After that time, a diet of salmon starter is suitable for rearing larvae to the juvenile stage.