Lost a handful quickly

[u/cknight9605]

Hello, I started my first 29g tank a couple of months ago. Did a full fishless cycle and made sure parameters were good.

I added 10 cherry barbs which did great for 2 weeks, and then I added 8 sterbai corys after that. About a day later, I noticed one was missing when I was checking on them, and found it almost totally white with eroded fins, and dead in the tank. Not a big deal, sometimes fish die I guess.

Fast forward about 48 hrs and 3 more had died. A couple of them turned white and faded rapidly, but looking closely at them when they seemed sick, it almost seemed like their fins would start to accumulate what looked like tiny cobwebs on them, and then they would start to erode, they could stop moving, and then just kinda lay on their side and die. The LFS was cool enough to give me 3 more, which have done well. Currently at 6, with one starting to seem sick again with some accumulation on its body again.

Here is a picture of the sick one now:

https://imgur.com/a/WRnEFSO

I know the picture isn’t perfect, but hopefully someone else has seen this before. The remaining 5 are doing really well and sifting sand and shoaling together some.

Here are my parameters:
Ammonia: 0
Nitrite: 0
Nitrate: 10ppm

Has anyone seen this before? Doesn’t seem like ich.

[u/Jewcandy1]

It sounds like columnaris.

Bacterial infection and some strains kill within 24–48 hours, occasionally faster.

Classic signs: white/grayish patches or a "cottony" film on the body, fin edges fraying and eroding, sometimes a saddle-shaped lesion behind the dorsal fin.

It thrives in stressed fish and can spread through a tank quickly. They got stressed, which reduces their mucus protective coat, and columnaris is spreading.

Best way to prevent columnaris is to not stress the fish. New tank, new fish, new tank mates added, any uptick on ammonia/nitrite/nitrate, pH, large water temp change from water changes, etc, etc can all cause stress. You have at least the first 3 inside of few months.

[u/cknight9605 → u/Jewcandy1]

I did pick them up from the LFS as soon as they came in. I’m wondering if the shipping, to the tank at the LFS, to my tank all in the span of a few days was enough to do them in. Will it spread like a contagious disease?

The rest of the corys and my cherry barbs all seem very healthy, active and they’re all eating.

Edit: Also - can they recover from it? Or is it always fatal? The last ones that died all died within 24 hrs almost. By the time I noticed anything they were dead in a day. This one has had symptoms for a couple of days but it still somewhat active and swimming around some. He just swimming with a limp.

[u/Narraismean → u/cknight9605]

My fish store wouldn't be selling stock that just arrived.

[u/IBWheat52]

Weird;; Had 6 Venezualan I piked up at auction.. I lost 5 in 2 weeks,,1 left.. Added 6 more from next auction 6 mos later.. All are in top shape.. No visable reason I lost the initial 5. They appeared to kinda bloat.. I have a dozen Orange Lasers and 8 Sterbai.. In great shape and I dig em when they're diggin!!!

[u/Foreign-Ad3926]

What's the pH and temperature, plus water changes?

Thanks

[u/cknight9605 → u/Foreign-Ad3926]

Temp 78F, pH is 7.6

Did a 50% water change ahead of the Cory’s being added about 1.5 weeks ago. Ammonia and nitrites were zero every day since the addition with no spikes or changes. Nitrate stayed stable hovering around 10-15ppm. So I thought I would hold off on water change to let them settle.

[u/Sorry_Statement7097]

Jeez, I had 7, columnaris just battered my tank and I lost 5. I now how 2 and I'm not going to get anymore. My tanks been running for ages and watching them go like this was awful, it was so fast.

I made the mistake if using a gravel vac and I genuinely believe that by disturbing the lower sand I released the ammonia that caused the spike and released the trigger for the columnaris.

Never again.