Full and Partial Overhead Tank Cover Improves Rainbow Trout Rearing Performance

This study examined the effects of different overhead tank cover regimes during rearing of Rainbow Trout Onchorynchus mykiss. Three different overhead cover treatments were applied to circular tanks: near-full (98%), partial (65%), and no cover. Compared with tanks with no overhead cover, fish growth and feed conversion ratio were significantly improved in tanks with either partial cover or near-full cover. There were no significant differences in condition factor, visceral somatic index, hepatosomatic index, or hematocrit values in fish reared under either of the cover treatments. These results indicate that either partial or near-full covers may provide benefits during hatchery production of Rainbow Trout.