Get an upclose picture of the spots and post the picture in the freshwater disease section, you'll get a higher response rate. What do the spots look like? are they raised off the skin? black spot disease is caused by a parasite I do believe, and they leave noticeable black lesions on the fish, similar to ich but black instead. myxobacteriosis tends to show itself as black, white or red spots/lesions from what I remember reading about it forever ago. I could wrong but a picture is worth a thousand words in this case. I would get a wide spectrum bacterial med such as quick cure or even methylene blue to treat the tank with. Also I'd get some Seachem paraguard to cover any parasitic issues. P.S. What part of OH are you in? If you ever decide the fish needs rehomed shoot me a message, I can accommodate him well. Not saying you aren't doing a great job so far but it sounds as if your hands are tied on an upgrade tank for him. Awesome job thus far though!