Black Neon Tetras keep getting finrot & random deaths

[Luananeko]

I've been battling issues with my 75 gallon community, and I'm totally baffled on what's wrong... I think I've lost my entire dwarf chain loach school (haven't seen any of them in days when they used to be super active and out and about), and my black neon tetras keep getting fin rot. None of the dwarf chain loaches seemed sick, they just started hiding more and only occasionally I found a body (downside of heavy planting, can't find corpses before they're scavenged).

I've tried quarantining the tetras... Some die, some get better, and the ones that get better seem to randomly get fin rot again later back in the main tank, so I've tried a full round of anti-fungal meds (which is a PAIN on such a big tank)... Everyone seemed good, but now about a month later I'm seeing the darn white tufts on the black neons again.

Tank stats:
75 gallon planted medium light/low tech community
pH: 6.5
Ammonia: 0
Nitrite: 0
Nitrate: 10
4-5 inch gravel/eco-complete substrate with thriving blackworm population
Rena Filstar XP3 filter
50% water change weekly

Inhabitants:
5 gourami (1 pearl, 2 opaline, 2 blue)
1 king betta
2 Neon Tetras (down from a school of 8 before the issues started)
4 Black Neon Tetras (down from 8)
5 male guppies
1 Red Tail Black Shark
2 adult ADFs (they get target fed every other day)
Waaaaay too many snails that originally hitchhiked on the plants...

Casualties so far:
6 dwarf chain loaches
4 Black Neon Tetras
4 Neon Tetras
2 Honeycomb catfish

Any idea what the heck's wrong? The tank looks so empty right now, but I don't want to even think about restocking until I figure out why I keep losing fish...

 

[Hholly]

Could it be columnaris? Which is, I think, a gram negative bacteria. There are meds for that, of that's what they have. Good luck. Sorry for your losses.

 

[Candiceg]

I thought columnaris was a red worm that you would see coming out of the fish's anus. Am I wrong?

 

[Hholly]

No that's camellanus.

 

[Candiceg]

Oh thank you my bad

 

[Luananeko]

I've never dealt with columnaris before, so I did some looking up... It definitely looks like it could be confused with the fin rot I thought they had. I've put some salt in for now to hold them over until I can pick up some meds on the way home from work. Here's hoping it does the trick!

I'm a little confused how this got introduced to the tank though, as it sounds like bad water quality & stress causes it... My tank's always at 0 ammonia, 0 nitrite, and usually never gets above 10 nitrate thanks to the plants... The only source of stress I can think of would be that the shark occasionally chases the tetras, but its nothing more than a shooing type chase away from his tree stump. Everyone else ignores the tetras. Any ideas? I don't want to go through and treat everyone just to have it crop back up later because of some inherent issue with how I'm caring for the tank...

 

[Hholly]

It could just be one unhealthy fish started it. It's very contagious. I've heard of lots of cases in tanks that were well cared for. Don't think it's any lack on your part. But you have to treat it aggressively. Good luck!

 

[Luananeko]

Well, that's comforting to know at least... Definitely going to treat the entire tank then if it's that contagious. I want this thing completely gone! Thanks!

 

[Candiceg]

Since its contagious if you have multiple tanks make sure you don't mix equipment up.

 

[Luananeko]

Only the one tank right now, not enough space for as many tanks as I'd love to have eventually Thanks for the warning though!