J. R. Reed

Investigations have shown that small (less than 10 cm) channel catfish fingerlings, Ictulurus punctatus Rafinesque, gained as much weight in a 10 week period on a diet of 25%-75% oxidation pond algae-commercial feed as did control animals fed 100% commercial feed. Larger fish (20-25 cm) fed the algal-supplemented diet did not gain as much weight in 10 weeks as did control fish on 100% commercial feed. Whole body protein and fat levels did not differ significantly between control and experimental fish.

Two cyprinid fishes, rlinostomus funduloides and Notropis cornutus were tested with naturally occurring substances including some well-known biogenic amines. Behavioral responses to histamine were similar to those observed in previous tests with natural alarm substance extracts. A response threshold was obtained at 0.01 ppm. Spectrophotofluorometric emission spectra also indicated that the natural alarm substance known to exist in many species of fish may be a ringed or double ringed compound.