i noticed this morning that my male severum had a few pimple like growths on his lower side. he will get one, usually in the same spot, higher on his body more towards his caudal. it usually goes away after a few days. this time i noticed two or three little growths. i treated with a little melafix but should i use something else? i just did a 50-60% water change on tuesday, as i do once a week. ammonia is 0, nitrites are 0, and nitrates are 0 and pH is about 6.5. the area around where the growth is looks a little rough. any ideas what it is?