Metro is safe for your bacteria. You may want to euthanize him. I would treat your whole tank and then mix up a paste from nls, garlic, and metro. Try to lower stress, keep lights off. keep water perfect as possible. Make sure your only feeding NLS for now. Im not sure what your stock is. Just make sure its what your supposed to be feeding them. Some sources say bloat is caused by food like blood worms, and beef heart. Dosent agree with mbuna.. Also I dont feed my fish on Wednesday. Giving them a fasting day is supposed to help. check out the seachem website for dosing instructions for metro