Most nano fish >1" are bottom dwellers. Elacatinus oceanops (neon goby) has always been in open waters somewhat for me.
Firefish is a great nano fish, I have three orange firefish in a 28 gal with refugium. I have had the trio over a year, little aggression. They swim as a group it the wate column.Fire fish would be too big.
I will add a 20G fuge or bigger in the future. Feeding pump from Biocube 1st chamber into the fuge.. then gravity drain it back into the Biocube.