OK so my large cave fish appears to be a little unwell.

He’s just laying on his side not moving unless something else swims into him or i poke him.  He’s hardly breathing takes a few gulps then stops and goes back to laying on his side.

There’s no visible marks on him of any type and all the other fish in the tank are fine.  All I can think is its simply old age catching up with him he’s proabably a good 4 years old now.

Water testing shows the water in tip top condition and to be on the safe side I’ve put an anti fungal  treatement in too.  There’s plenty of water movement and surface displacement for oxygenation.

I’m completely at a loss.