Rainbow trout fry in rearing trough at Genoa NFH. - FWS photo

The Genoa National Fish Hatchery received 460,000 rainbow trout eggs throughout the winter from the Ennis NFH. The majority of the resulting fry were reared to as much as two inches in length by April. 

During this time they have been used as forage to feed approximately 15,700 host fish primarily for the endangered Higginsi Pearlymussel. The host fish consist of largemouth bass, smallmouth bass, channel catfish and walleyes.

These 5- to 6-inch host fish have been held in an icy 1 acre pond throughout the winter at the Genoa NFH. In early April these fish will be harvested from the pond, and then placed in rearing tanks until the time is right to artificially inoculate larval mussels on their gills for restoration and recovery efforts within the upper Mississippi river basin.

By the end of the cold winter, these host fish are in excellent condition. But, as temperatures rise, so does their hunger.

One problem that the staff faces is the possibility of compromising the health of the host fish if they are fed a forage species which may harbor diseases and parasites. Fortunately, this chance can be reduced by feeding a certified disease free forage base to the bass and walleye.

This is possible thanks to the rainbow trout eggs received from the Ennis NFH which has a disease free classification, and that rating is maintained throughout the rearing process at the Genoa NFH. Thus, the rainbow trout forage ensures healthy and well fed fish throughout the mussel propagation season.