What killed my fish?

[swifty]

Well, I woke up this morning and noticed 1 of my 12 tetras alone from the group. Upon closer inspection he seemed to have a large red mark on his side. He was swimming pretty slow and looked like he was in bad shape. I felt this was a good time to use the vodka/frozen water treatment for a fast euthanization, which surprisingly, it was.

I thought it was some sort of internal parasite or a infection, but after getting a good look, it actually looks like something took a mean chunk out of its side.

It was one of the 4 new long-finned skirt tetras that I bought, of which they're the first fish I've ever bought at petsmart (all other fish have been bought from LFS).

I have a 3.25" firemouth, and 11 long/short fin black skirt tetras in my 29g now.

Could he not have been accepted and attacked by the school, or was he a victim of my firemouth? My firemouth has never shown any aggression to the tetras and was raised with them from 1.5" for the last 7 months.

 

[Wiggles24]

If it were me I would of used melafix or something similar first to see if the wound would of responded before I euthanized it. But in response it could of been your firemouth just because its never shown aggression before doesn't mean it's temperament wont change as it matures. Keep an eye on it

 

[Scottyhorse]

I've had injuries like that before. There is nothing that can be done for them.

 

[swifty]

I went from severe guilt to relief reading those 2 posts.

I did debate attempting to nurse it, but it was in a corner of the tank just treading water. I read of fins healing but never actual flesh or wounds like that, so I felt that was my only option.

I'll continue to keep him under watch, and if it comes down to it I'll remove the tetras and take them to my LFS.

 

[DevoPast]

I had a problem like that in the past where elevated pH was causing skin lesions like that in my danios. Check your water parameters to rule that out! It started with one fish before quickly affecting many.