sick peesh

[bolivianram123]

umm one of my fish had that disease where the tail turns white and they lose control of it. I've seen it before in my friend's tank but that was a long time ago. What should I do, i already euthanized the fish.. should i do waterchanges? i don't understand how this could have happened, I always do weekly water changes, heck i did one yesterday. :<
I really don't want this spreading since ive got my CPD in there too. so, help? i would google, but i don't know exactly what to look up.

[mizu-chan]

Oh goodness. I remember that disease. ):

I didn't read everything but these sites might help: here and here.

I think it's Costia, now that I read more, but I'm not too sure.