What killed this oto? (warning: dead fish pics)

LeahK

LeahK

AC Members
Jul 5, 2007
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So, I've had my otos for several months now, and I thought they were all doing really well. But this morning I found one dead, and I'm trying to diagnose what killed it, so I'll know if I need to worry about the rest of my fish.
The tank is established, 0 ammonia, 0 nitrites, nitrates between 10 and 20. The inhabitants are in my sig. Nothing new has been added since these otos in March. They were in QT for 3 weeks before going in the main tank.

About three days ago, I noticed this oto had a white patch on its head. It didn't look fuzzy or weird, it just looked like a scratch. I'd seen similar scratches on scaleless fish in the past, like a white streak, and they'd always healed up on their own, so I didn't worry. I don't usually medicate my tank, but I decided to add some melafix, because the tank pushes 81 degrees in the summer and I know the heat breeds bacteria. I dosed for 2 days, and the scratch started to get smaller. I also did large water changes to keep the water clean. I thought everything was going fine. I started running some carbon yesterday to clean out the melafix. All otos were alive and looking well, as of yesterday afternoon.

Then, this morning, I found the poor guy who'd had the scratch dead under some driftwood. His eyes are gone, and his stomach looks weird. It's very dark, the color of the algae he eats. His stomach was white and round when I last saw him alive.

I'm worried that:
1) The barbs killed him. Why are his eyes gone? It's kinda disturbing.
2) The white scratch was really columnaris and I'm about to have an epidemic on my hands.

Here are the pics: his eyes, the top of his head with the white scratch, and his belly.

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If they aren't showing outward signs then it's probably not a pandemic.

I don't keep ottos myself but they seem sort of delicate. Yours being wild caught could have been any age, exposed to any number of toxins or hardships that would shorten its lifespan. So there's no telling if it was even ill, absent symptoms. My best guess is that the wound was a pathway for an infection, and that the fish was in less than perfect health due to age, condition or predisposition.

Throw in a couple extra water changes this week, and monitor for behavior and/or other discoloration. Even considering "the missing one", you've had pretty good luck with them, compared to some.
 
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With what you've said about your fish and your tank and your tank maintenance, I wouldn't worry much about it. Fish die sometimes and we never figure out why. The white spot on his head could have even been a scrape from darting or a little heater burn from the heater. It doesn't seem likely that you've got an outbreak of anything going on. Like Zebulon stated, keep up with some extra water changes, especially since you had a dead fish in the tank for a little while and keep an eye on them. Though this doesn't sound pretty, fish usually go for the eyes and head of a dead fish when they start eating it. And lots of fish will feed on a dead fish body, it's just nature at work. Sorry you lost one.
 
Thanks, that makes me feel a little better. I was looking back over my old posts, trying to get my dates right. I bought the group of 6 otos on Feb. 28. They went into the main tank in mid-March. Around April 10, one went missing and I never found its body. Then, I lost this poor guy today.
So, the two deaths are stretched out over time enough that they probably aren't related. I'll just keep and eye on things and keep my fingers crossed.
 
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