i woke this am to my healthy dojo loach (12 inches long) having a raised reddened bump on his skin. i do not know if this is an external or internal cause. i treated the water for bacteral issues, for parasite issues and added melafix. i have a dojo loach in a community tank with now an angelfish, 2 clown loaches, and a grommy fish (5 total). i keep a clean 55 gallon tank, and do a 50 to 75 % water change every 2 weeks, with filter changes. i rinse the filters every night to every other night. we just had our Koi (9inches long) die yesterday, so thats why i treated the whole tank thinking it was a community issue. any ideas or hep welcomed, as i have been searching all over the internet and havent seen the same bump as my loach has pictured anywhere else.