Yes, there are fish in Long Tom and Mountain Home reservoirs. Mountain Home Reservoir is typically stocked with rainbow trout in the early spring. Fish will survive all year if adiquate water remains in the reservoir over the winter. If conditions are right, this can be a very nice ice fishery.
Long Tom Reservoir is mostly on private property The owner has stocked it with rainbow trout in the past and there have been hatchery rainbow trout wash down to the reservoir with high-water events. There are also wild rainbow trout that are caught in the reservoir that were produced in the tributaries.