I would start with 4 to 6 firemouths, and let them pair off naturally as
they mature. A 55 gallon is large enough for two pairs of firemouths, plus
some tankmates.

Compatible fish include most catfish, most plecos, danios, gouramis ,
convicts, Sajicas, Salvinis , neets, jewels , kribs, daffodils, and many
others. Firemouths are likely to eat small slow moving fish, but might get
bullied by larger or more agressive species.

I kept a pair of firemouths and a pair of kribensis in a 55 gallon for
awhile, and got several spawns from both the firemouths and the kribs. Other
fish in the tank were giant danios , banjo cats , a bristlenose, and blue
gouramis.

Limnophile

"Len" wrote in message ...
I want to add some firemouths to a 55 gallon tank(no fish in it
currently, but cycled). I don't want the tank to become overcrowded as
they grow. How many should I start with. What other fish would be
compatible with them?