I bought a doliatus rabbitfish a few months ago and he started losing weight after about a month in my aquarium. His lateral line is very pronounced. He has been acting fine and eating aggressively. I have been overfeeding to try to get him to gain weight but he hasn't. I treated him in a bath with praziquantel about a month ago (24 mg/gallon) for three hours and he looks a little bit better but not by much. I can't afford to keep overfeeding the tank because my nitrates have been skyrocketing and corals are suffering. I was wondering if anyone else has had success treating internal parasites or if rabbitfish just have a high metabolism and need a lot of food. I feed him pellets, mysis, and occasional macroalgae. (all of the macroalgae gone in a day or so). I have a 50 gallon reef aquarium, no sump, HOB protein skimmer plus 2 HOB filters, about 40 lbs live rock, and a few other healthy docile fish. Water parameters within normal levels for reef except nitrates which are 25 ppm.
He also seems to have cloudy eyes, which he has had since I got him. Cyanide possibly?