Is this stocking OK????

Maybe a few khuli loaches for the bottom? They stay small and they're super hyper. Very fun to watch. :)
 
I would be concerned that the labeo bicolor would get to large for a 20 gal. Also being such a semi-aggressive fish, it may pick out a victim and harass it constantly.
 
Flagfish said:
Perhaps a red tailed shark? (labeo bicolor)? They are nice fish and have stunning colours.

Flag
No RTS in a 20g tank, that is wayyyy too small for them.

Your options are rather limited if you decide to keep the gourami. Being a tall tank you have less surface area for oxygen exchange. If you want to keep it the way that it is I would add a few dwarf cories or some snails and shrimp.
 
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