Suicidal otocinclus?

[rezende]

Hello guys,
I've got 3 otos around 7 weeks ago. Two of them were swimming together most of time, while the 3rd one never looked so happy. He was staying on top of filters, plants, gravel etc most of time, without so much activity. I have barely seem him eating... and he was always getting stuck between filter and glass, heater and glass etc. Looked like he was doing that on purpose, maybe lazy to swim, then he pushed himself in such places. I remember I had to release him many times until he succeeded...
One day he disappeared and I found him dead UNDER the bogwood

Well, 5 weeks after, another oto started showing the same "sadness"/"lazyness". He got himself stuck in the same places. I released him some times. Then he succeeded (pictures).



It's difficult to put something in this hole he went in. It was very difficult to remove him!! He was alive when I finally manage to get him out of there, but didn't survive longer after that.
But then, my point is: both otos were trying hard to get stuck! I don't consider my fish tank as full of "fish-traps" because those are really stupid places to get stuck (under the bogwood?!?), and I think they were already showing a weird behavior before.

My water parameters are (54L tank):
NO3 < 20
NO2 0
pH ~7.5
gH ~14°d
kH ~15°d
Bogwood and glass plenty of algae (unfortunately).
Other species: 3 mollies, 2 guppies, ~10 RCS

So, any idea of what could be their problems? Too hard water?! =/

The third and last oto has been the most active since the beginning. Spends the whole day sucking glass, plants, bogwood, and has NEVER got stuck anywhere.
He is alone now and I think it isn't good for him, but I'm afraid of getting more otos and end up having the same problem, without knowing the reason.
Should I get more otos and consider those fatalities just as "accidents"?

 

[imissmytruck]

I preface this with I truly know nothing about the OTO except they are awesome fish. So my LFS says to me...."get three or four as they are schooling fish". I said sure. Why not. I have one left that is a year old. I visited another LFS dedicated to only fish. Each tank has only ONE oto. What I believe happened to my oto (and yours) is that they are solitary fish, and though not truly territorial the dominant one chases the lesser into these tiny place to die. Therefore winning. I have kept my oto solo for the last year and he is happy. He defends himself against my Parkisoni Rainbow when he's feeling frisky.

The long and short of it...keep him solo. It worked for me. And yes....I do know that goes against ALL the info you can read online about OTO's.

GOOD LUCK!

 

[absolutangel04]

I have kept a good handful of otos over the years, but singly and in groups. I disagree entirely that they are territorial and that one fish chased your others into those positions to die. They are indeed a social fish, and not a generally territorial in the least. That said, sometimes you will get a more dominant oto who does better alone. After all, fish are individuals. I don't believe that you had a dominant oto chasing your others though. It sounds like you had the classic oto experience which is that many of them tend to just slowly waste away and die in tanks. They are not a particularly hardy fish in most circumstances until they are well established in the tank.
In the wild, they have a diverse diet and when they are captured for the aquarium trade, their diet becomes much less diverse and they do not all adjust well. They are notorious for being finicky eaters and do not always transition to tank life well.
The otos who died were likely just sickly. They get themselves into positions like that because either they are weak and the current in the tank sweeps them there, or else to try and save energy because they don't feel good.
Generally, I prefer otos in groups. Though, I had one in my tank by himself for 3 years and he was fine. Adding more is up to you, but I suggest trying it if you can find some nice, healthy looking, fat ones from a store. All of mine have shown the tendency to seek out company when it was offered to them.

 

[rezende]

Thanks guys.
At least now I'm not that much worried about leaving this guy alone for while.
Maybe I'll get more very soon, but better to wait for my tank to establish. I'm having trouble to keep Bacopas (yes, I know, it was suppose to be easy ), then I'm injecting CO2 to see what happens...
More plants will make me more comfortable to get more otos.