Therefore, a controlled study was conducted that would aid in the establishment of a chronic nitrate nitrogen threshold for juvenile rainbow trout by evaluating the potential effects of 80–100 mg/L NO3-N on trout performance, health, and welfare. Theresearch described herein was complementary to Davidson et al.(2011a) which identified NO3-N as a potential cause of rainbowtrout health and welfare problems in low exchange WRAS