Any that say they must not be used on RTCs, albeit I am not aware of such and never encountered such.
Many would say "Do not use on scaleless fish". That USUALLY means half-dose would be fine or recommended. I even used a full dose of such meds on many of my catfish (all catfish are scaleless) without any problems... but the cat should be in good water, on a good diet, and had been long healthy and vibrant beforehand (before the illness occurred).