PS Forgot to mention, the behavior of the otos did not change with the black background. They are still extremely shy. They are invisible during the day. If I stalk the tank after lights out I *may* catch sometimes a glimpse of an oto, but it bolts away as soon as I make the slightest move. I cannot ...

adding a dark background to the tank That did the trick. I added a black background and their behavior changed overnight. They now act exactly as they did when I bought them - they stay out in plain view. They don't play or chase around much (they just sit on their bellies 80% of the time) but at ...

Thanks all for the comments and advice. Mats, I'll try adding a dark background to the tank. In my opinion they already have enough places to hide (see the photo in my first post - the fish are hiding well enough, right? :) ). Marc, no, noise level did not change since I have the aquarium, it's ...

I apologize for the cross-posting, but since it involves otos as well as corys I am reposting a link to my message where I am asking for help:
http://www.planetcatfish.com/forum/view ... =6&t=33492

Hi, I have 5 Cory Sterbai and 6 Otos (at least 2 species, I'm unsure which exactly) that during the last four months or so have become increasingly shy. The corys have gone from happy aquarium clowns, that played all day if full view, to invisible recluses. If they happen to be in the open and a ...