Fire mouth Cichlid

IMO and IME a firemouth is far too big for a 20g with no other fish. Sorry to be the bad news guy. but a 6" cichlid is just too much.
Dave

Sorry will have to agree there, 6" fish of just about any kind are to big for a tank of that size it just wouldnt be fair. If you particularly like Cichlids try some of the dwarf verietys like Rams or Kribensis.

Yes as said above a 6" Firemouth should not be housed in a 20 gallon tank but it takes them at least 2 years to get to this size and you can upgrade later. But the Tinfoil barb really has no place in anything less then a 100 gallon + and 6 foot long tank. These barbs grow very big ( 12" + is not uncommon). Give the barb back and start over with some small Tetras and if you want cichlids go with some dwarfs. Here are a few suggestions for you to research before you buy anything.

Nannacara anomala
Nannacara aureocephalus
Nannacara taenia

Laetacara curviceps
Laetatcara dorsigera

Crenicichla compressiceps

Biotodoma cupido

Cleithracara maronii (keyhole cichlid)

Anomalochromis thomasi (African Butterfly cichlid)

Microgeophagus multispinosa

Pelvachromis pulcher (Kribs)

firemouths grow very slowly in my experience (i have had one for over six months and he has shown very little growth) so if you are willing to upgrade I would say it is possible...and you will absolutely have to upgrade if you want to keep that barb (they get gigantic)

Barbs are great, but keep in mind they do like to be kept in schools of 5 or so. Good luck.

if it were a 20 long i would say a single FM would be alright. no matter what i would ditch the barb, i just say a 12'' tinfoil barb at the lfs

ryan