Oto catfish not eating

[saiwong]

Hello,

I have several oto catfish and other louches in a well established cycled tank.

Everything has been fine for many months but recently found one oto catfish very thin and not eating like the others (who all have fat bellys). I've seen this oto being chased by another but don't know if this is just playful chase, mating behavior or other harmless activity
or bullying (causing stress)? I've tried isolating this oto in a breeding box and given it alot of different foods but he seems uninterested in eating any.

I've investigated internal parasites, but the oto's poop is the standard grey/black colour (i.e. NOT white) so currently suspecting a stress issue


Any advice?

[BigBen]

It won't be aggression from oto to oto. Feed some veg. Courgette or pepper.

[plankton]

Yes, if there's no algae they need fresh veg as well as algae wafers.
Cucumber has lots of vitamins (but not a lot of bulk). I've tried most things, but courgette, pepper (NOT green) and cucumber seem to be the most readily accepted by them.