Losing Fish Possible Columnaris?

[sfgiants13]

A while back I had a big outbreak losing about half my stock that I never was able to figure out what it was. The shop I got them from isn’t what it used to be and some of the tanks had dead fish so no doubt something I brought home. I had 2 ich outbreaks and that’s what has me leaning columnaris. For about a year now I lose one to two fish every month or two. They bloat up and are gone within a few weeks usually. No other noticeable symptoms but now I’m noticing some redness on one of the neons while it looks like another

bloated one may have died and got eaten. I’ve attached a photo.

I’ve tested the water many times and it’s 0 ammonia nitrite and usually around 10-20 nitrate. Ph around 7.5 and I run co2. I’m trying to figure out what this all is. I haven’t added any new fish in well over a year so now what’s left is about 8 corys 6 neons and 8 zebras.

Not quite sure where to go or if this tank can even be saved. It’s been issues nonstop and I just can’t seem to figure out what’s causing all of these deaths.

 

[Goldfish4EVER]

I think you need to do a deep clean in the entire tank. Try to clean the plants or replace them, clean the rocks, ect. It could be the fish's problem though. If cleaning doesn"t help, then switch out a tank.

 

[DoubleDutch]

One thing is quite clear : It is not Columnaris.

 

[sfgiants13]

Any idea what it could be? Just trying to get treatment options before nuking the entire tank.