I would do the tetras instead of the mollies for sure. I wouldn't do giant danios, instead how about pearl danios? (Danio albolineatus)
As for the 20g, that looks better, but not perfect. I wouldn't do the ghost catfish, how about something smaller/
I'm pretty sure my DG is on his last day.. I don't want to get another one if he passes, so is there anything else that would be a good centerpiece for the 20+ long?
Here was the stock:
3x Dwarf gourami (1m,2f)
8x Ghost catfish
12x Kuhli loach (6 striped, 6 black)
1x Clown pleco
5x Amano shrimp
10x ghost shrimp
10x Sunkist shrimp
1x Mystery snail
3x Rabbit snail
I am not aware of very many middle-dwelling fish which aren't schooling. Most of the common centerpiece fish are top- or bottom-dwellers, with the exception of angelfish which aren't what you're after here. There may be options I'm just unaware of...
It can be a top dweller, I just didn't want it to interfere with the hatchet fish.
Maybe I could do this?
6-8x Ghost catfish
6x sparkling gourami (are they schooling fish?)
12x Kuhli loach
1x clown pleco