Did you ever take a stab at it's identity?
> I have offered live brine shrimp to the gudgeon, he took a mouthful
> and then spat them out ! I have offered live black worm but he has run
> from them.
That's pretty impressive! :-)
> I do have some of those transparent shrimp (ghost shrimp ?)
> in the tank, could he be living on those, or is he eating some of the
> decaying leaves that are in the tank ?
Do you ever see it's stomach enlarge from eating something large like a
shrimp? They probably don't tend to eat decaying leaves. Shrimp would
certainly be fair game. Perhaps try either or daphnia, mozzie larvae, or
very small fish. Your problem is unusual, I've normally found gudgeons
and gobies pretty easy to adapt to aquarium conditions. Best of luck!
Tootles
Peter Unmack