I have both. They are both extremely Hardy fish. They withstood 80ppm or nitrates for awhile . I wouldn't worry about it to be honest. They are tuff.. the redtail is 18" not sure about the tsnLove this thread, my RTCxTSN has been growing at an insane rate. He was 5 inches on May 7, yesterday he was just under 9.5 and it hasnt even been a full 4 weeks! I really want to get a RTC but I am worried that they are harder to take care of than my RTCxTSN, I hear they are sensitive to water, my nitrates usually pump up to 40ppm between each water change (Nitrite and Ammonia 0)