If by Asian stone catfish you mean Akysis, then I would suggest these to be a little to small and would be at risk. Whilst banjos are not hunters and are quite a lazy catfish, I have had mine quite a number of years and have never seen them eat, but they can be a more opportunistic feeder, so if the stone cats came across a half burried banjo there would be no sure ending.
I have kept banjos with forties fine. And I have kept Akysis, but never all together.
As an extra, banjos can bury in gravel but sand would be ideal.
if you hope to breed them, the little I have found indicated that they spawned on the glass where a sprayer return fed back. However another report on here suggested a different setup.
you will easily tell the larger father females from the skinny smaller males as they grow.