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[greysong5]

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[PASoracco]

the yoyo shouldn't be living alone, or with anything that will nip at it. If you are going to house it with fish fast and aggressive enough to chase it down and chomp on it, at least give it hiding places.

a 2.5 is waaaaay to small for a single yoyo anywhere near full grown. Yes the fish needs to be isolated from the attacked, but in a 10 gallon, at least. a fully grown yoyo could barely turn around in a tank that size, let alone comfortably stretch its fins. taking the yoyo out of the large tank and shoving him in this tiny box probably stressed him out even more.

did you use old/cycled filter material in the new filter or fill the tank with water from the old tank? you said the fish was placed in fresh water, which would cause osmotic shock, and be incredibly stressful and painful for an already injured fish.

you sprayed the fish...with neosporin? don't do that again! use fish medications for fish, not people medication. Most (all?) loaches are scaleless fish, and are incredibly sensitive to ANY chemicals, let alone whatever the heck they put in spray neosporin. I'm amazed the fish is still alive.

put the fish in a larger tank. use filter element from the old tank, and try and match the water parameters as closely as possible. Give the fish a soft sand substrate, and tons of hiding places. Dose with melafix or something similar for the wounds.