Data and code release to evaluate a continuous-flow streamside toxicity test that was conducted with common logperch (Percina caprodes) and larval sea lamprey (Petromyzon marinus) to evaluate the risk posed by 4-nitro-3-(trifluoromethyl)phenol (TFM) sea lamprey control stream treatments to logperch. Logperch are a host to the parasitic glochidia life stage of the federally endangered snuffbox mussel (Epioblasma triquetra). Streams with an extant population of snuffbox must be treated before May 1st to prevent inadvertent take through TFM-related mortality of glochidia-infested fish. The concentration of TFM required to induce 99.9% mortality of sea lamprey was 6.52 mg/L and the concentration of TFM required to induce 25% mortality of logperch was 10.14 mg/L. Our data show that logperch are not as sensitive as previously demonstrated and may result in the ability to treat streams after the current May 1st restriction. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.