Concerned for these fish

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Apr 11, 2023
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I have put my corydoras and otocinclus in their new tank. It's cycled. Parameters are perfect. I'm concerned by two of my fish, though.

The cory's tail has been like that for a while. I didn't set up the old tank correctly. There was large gravel pieces and she injured herself. I'm concerned by the strange belly and the curve of her spine.


As for the oto... it got fat overnight. I've been watching them, and that oto was not that big a few days ago.


Any input would be much appreciated.
I noticed this morning that the oto's eyes are bulging. So I moved it into quarantine. I'll figure out what to do when I get home from work.

Any advice on how to treat dropsy in an otocinclus? Or is this guy far gone?
Otocinclus will not do well in newly setup tanks; they need to constantly feed on algae to survive, which will not be present in a new setup.

The one pictured may have worms, hence the bloated stomach, but I am no fish disease expert, by any means; not sure what's going on with the cory, either

@Colin_T , have a look...
Hello. Hard to believe the tank water chemistry is perfect if you have unusual behavior in your fish. Trying to figure out if there's a problem is very time consuming and you might be wrong after all the time spent trying to figure things out. I'd suggest a simple water change. One that's slightly larger than normal. If you're not removing and replacing half the tank water weekly, your fish won't be their healthiest.

10 Tanks (Now 11)
I know now that otocinclus should be put in an established tank. I got these guys a year and a half ago when I had no knowledge. The cory isn't acting strange. She's swimming fine, and eats like a pig. She has some balance issues due to the broken tail fin, but other than that she's very active.

And as for the conditions... I'll be honest, these fish were not in the healthiest conditions before I put them in this tank. It's a long story. I was living with a roommate who hated that I owned fish, and he put the tank in a cabinet where I couldn't do any maintenance. No one would adopt the fish, either. So, I have tried giving them the best life since moving into my new apartment. Maybe the time spent living in those conditions has caught up with them.

I do 30% water changes every week in the new tank.
I will bow to advice from the disease-experienced members, but if this were me I would not worry at all about either fish. I had a cory with a deformed tail like this one and it lived in the group (it was C. sterbai) for over a decade. And I see nothing external to worry about. I see nothing wrong with the oto, they eat a lot of algae and get thick. If you have had it for over a year, it is obviously finding food and probably eating artificial foods like sinking green-base disks by now.

I would increase the volume of water changes to 50-60% once weekly. Provided the parameters--these are GH, pH and temperature here--are the same, you can not do any detriment with water changes.
I agree with Byron. A deformed fin won’t matter much to the fish. And the Oto just looks like it’s had a good meal.
Hello, updates on these two fish.

The corydora unfortunately passed away. I noticed she was breathing really fast for a day or two, then I found her on her side. Gills barely moving and she looked like she had internal bleeding. So I euthanized her.

As for the oto... I noticed there was a strange bubble around its cloaca. So, I took it out to get a better look and it also has some bleeding... I might euthanize this one, too.


I don't know what's going on. I have lost these two, and several juvi cories. I quarantined long enough. My ammonia, nitrite and nitrates are all 0. I've been taking food out since the cyano bacteria started. I've been trying so hard to clean it, but it's not going away. With the loss of my fish and these outbreaks it's been a little discouraging.
So sorry for the loss of your fish…

Normally when you cycle your tank, the nitrates will be at 5-20

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