We used mesocosms to evaluate the effects of drought on Nothonotus moorei (Yellowcheek Darter) and Nothonotus juliae (Yoke Darter) survival, growth, and behavior. Survival was low and did not differ between treatments. Yoke Darters gained mass in control treatments, whereas Yellowcheek Darters did not differ between treatments. Habitat-use varied between treatment and species, with control fish using all habitats and drought fish using run and pool habitats. Yellowcheek Darters had lower tag mortality than Yoke Darters. This study provides information to help conserve these species and many other stream fishes.