Ok, I've done a 15 gallon water change he is in a 40 gallon grow out tank. Tomorrow morning I'll be doing another 15 gallon water change which should get all of the melafix and kanamycin out of the water as well as the carbon I've put in. I've got one more question, could he be constipated? As a knife fish I've assumed that all he needs are pellets and meaty things. Maybe I've been feeding him wrong. God I'm so embarrassed he is such a special fish I want him to be well! In my research I've found that things like insects with their exoskeleton or canned vegetables can help him relieve himself, or an Epsom salt dip? I feel like I could do all the research in the world but it means nothing without the prior experience! Lol never thought I'd get so attached to a fish!