weird oto behaviour?

[Elle2]

My oto has taken to swimming upside down along the surface of the water as though he were sucking algae from the surface.

He has never done this before so I was wondering if anyone else has seen their oto do this, or whether something might be wrong with him. He seems normal in every other way and his belly generally seems full. But he is doing this surface swimming quite a bit.

 

[dskidmore]

I've never seen my otos do this, but I have snails that will. Do you have any surface film on the water he may be chowing on? Otos eat biofilm as easily as algae. This is why starving otos will latch onto fish, the fish's slime coat will do in a pinch.