Frozen Fish in Hatchery Diets May Be Dangerous

Abstract

Summary 1. Six experiments were run at Hackettstown and three at Leetown. From these experiments it appears that the inclusion of frozen and stored fish in the diet of trout produces good growth and with rainbow trout helps to produce good yields of eggs of superior quality, but that there is danger to the health of the fish from its continued use: 2. For yearling brook trout, 40 per cent of herring (Pomolobus) in the diet was very destructive, causing trout to turn black, become fungused and frequently blind, and eventually to die in large numbers. With as little as 24 per cent, this trouble also developed and caused loss. 3. For rainbow trout it appears that 24 per cent of herring is safe, but that 40 per cent produces a similar condition to that produced in brook trout after seven months' continuous use. 4. An experiment, in which mixed salt-water fish replaced the herring, suggests that the latter may be especially harmful. Unfortunately, it proved impractical to test the effect of fish which had not ...