I love these "mudfish" - they're in our rivers also, I used to keep on purpose but these days I end up with tiny juveniles as bycatch with shrimp, or they come with a waterlily. I've been trying to get juvenile of the BIG & toothy mudfish (bigmouth sleeper), but they're too quick & smart for me, same as the flag-fin types.
The "sandfish" goby is pretty fantastic in the aquarium, but destructive to plants in both digging/burial & here&there munching on leaves... i need to move him out of the 240, heartbreakingly.