Ok so I have this loach. I've had him for about four years and suddenly he comes out one day with a giant sore on his side. It looks like an ulcer or injury. I don't want to lose my loach as I've become quite attached. He is housed in a 20g with zebra danio, ghost shrimp, and african dwarf frogs. All of said tank mates have been with him for years except for the shrimp which were added three months ago. I have moved him to a smaller nursery tank with my tads. Photos are enclosed. Please let me know how to proceed.