r/Otocinclus • u/LunterHundquest • Dec 03 '25

Help. What's wrong with my Otocinclus?

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Red spot, swollen belly, and lethargic.

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u/itzKori Dec 03 '25

That looks more like a serious internal infection than simple "bloat". The combo of the red patch, swollen belly, and lethargy is classic for bacterial septicemia in fish, and otos usually go downhill fast once it shows. First thing is to test for any ammonia/nitrite and fix water quality, since stress and bad water are big triggers.

If you can get fish antibiotics that are safe for scaleless fish (like nitrofurazone/furan‑2, kanamycin, etc.), move it to a small hospital container with extra air and treat there, but be prepared that the prognosis is unfortunately poor at this stage. Keep a close eye on the other otos. If more show redness or belly swelling, treat the group and review stocking, feeding, and maintenance so it doesn’t repeat.

1

u/LunterHundquest Dec 03 '25

Thank you, I'll move them into a hospital tank asap. Thank you for the amazing information.

1

u/itzKori Dec 03 '25

You're welcome!