You know, I was thinking that it might be columnaris after the fact...it definitely hit and spread fast

I've never actually seen/dealt with it before..so I wasn't sure :/ Though the pictures I'm looking at now on google look just like what he had....poor guy
I'm waaaaaay to scared to use bleach, would hot water and through scrubbing suffice? Thats what I've done; I rinsed
everything in super hot water, scrubbed it all thoroughly, the soaked it in hot water, and I'm about to go empty it, scrub everything down, then dry it all off and it'll probably sit, dry, for a day or too....any bacteria should be killed when its dried out, right? At least, anything I may have missed?
Also...is this something you think he may have had before I got him even? I'd hate for this to be due to something I did wrong D: