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Hi

I have an otocinclus, he is in an 80l tank with guppies and platies. I did used to have 2 sucking loaches in there too.

Recently I noticed open wounds on a couple of the guppies. Of course my first thought was the loaches...I removed them to my 240l and have had no problems in there.

BUT, I then found more guppies with wounds, about a week later. So I am assuming the culprit must be my oto.

Is this normal for an oto? Is there any way to prevent it? He has a lovely round tummy, is fed courgette, cucumber, and a range of pellets, tablets and wafers, and the tank as a whole get occasional brine shrimp and other meaty foods.

I really don't want to have to get rid of him, but so far I have lost 5 guppies to the wounds.

Any help appreciated.

While some individual otos occasionally attack other fish, there's rarely any wounds - most of the time all you notice is that the fish get extremely agitated during the night and that, if they're small fish (to the size of, say, a platy), fish which were healthy in the evening are found dead in the morning. Presumably they die from the shock & stress when the otos eat their outer skin and slime layer. Larger fish survive being gnawed on, but are extremely stressed.

Open sores on living guppies to me more sounds like bacterial infection than any sort of attack, to be honest.

I have had three guppies that have had sores...two of them showed a circular-ish patch where the outer layer seemed to have been removed and a very small crack-like bleeding area. The other simply showed a circular patch that should have been black, but wasn't anymore.

These all died.

The other two I found showed no signs of infection or had any problems the previous night, they were floaters by morning though.

I have also lost a platy this morning, with no apparent infection or wounds. I have put the oto into a breeding net and I am going to see how things go over the next few days.

The fish are currently being treated with Melafix (daily) , which I normally put into the tank when cleaning, changing water or handling fish.

I keep otos in most of my tanks and have never seen such a thing. peaceful little fat bellied guys they are.

are yours getting enough to eat? Not that I think it's them or anything but you know just curious cause sometimes they say big pl*cos will suck slime coat but if I am not mistaken that 's just when they are starving.

Andywoolloo might be onto something. My oto's seem to want to suck on the twig catfish when their algae supplies are low. I try to keep a plant in a jar on a sunny shelf for just such times, they get pretty green in the sun and it's not a thick hair algae, just a little greening. I put it into the tank like a treat and the otos are there for days cleaning it off.

I put in cucumbers and other veggies but the twigs sometimes muscle the otos off it so they could very well be hungry even when I'm giving them what seems like enough. The algae covered plants do the trick. If you don't like the messiness of an algae plant, you can do the same simply by leaving a rock or a piece of wood in water in the sun. Algae will grow and you can hide it in the back of the tank while the otos get their fill.

Good luck and keep us posted of what your results are with the segregation of the otos.

My Otos suck on everything. They're always eating. If an object sits in one place for long enough, an Oto will attach itself. I also see it with Farlowellas (always hungry), Peckoltia (fry, less than 1 month old usually) and Ancistrus.
Amanda

Mike_Noren wrote:Open sores on living guppies to me more sounds like bacterial infection than any sort of attack, to be honest.

Just to update. I have had another go the same way, since caging up poor oto....Mike_Noren hit the nail on the head with bacterial infection. The last one to go, well I had to put her down, had a huge open sore and her tail was simply disintegrating before my eyes! Literally within 24hrs. I've since treated with anti-internal bacteria and am hoping I can at least save the rest of the guppies in there!

Sorry Oto...all is forgiven.

Quick question though....do you think I should have more than 1?

You should absolutely keep Otos in groups - in nature they are hundreds or thousands in one group, but in a smallish tank, you may want to restrict it to 5-6 or a few more (it's probably a good idea to buy 2-3 more than you actually want, as they aren't always the easiest fish to establish in your tank, because they are often starved in the shops/wholesalers).

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Mats