Brook trout
Brook trout inhabit Crooked Run upstream of their mouth and are the only fish inhabiting the stream at this point. In a survey 1997, their biomass at this location was measured to be 106.48 kilograms per hectare, which was the highest wild trout biomass of any tributary of Catawissa Creek observed during the survey. Brook trout less than 175 millimeters long make up 74.12 kilograms per hectare and brook trout more than 175 millimeters long make up 32.36 kilograms per hectare. The lengths of the trout in the stream range from 25 to 224 millimeters. Brook trout, brown trout, rainbow trout, and tiger trout were all observed in the stream upstream of its mouth, but many of these had escaped from the nearby Zion Grove Trout Hatchery.