Harlequin rasboras, Guppies, Platies, dwarf gourami, Tetras, Barbs, Danios, and Cory Cats to name some.
There are different species with different requirements in those groups but they would be a good start and are all fairly easy fish to find at the larger chain stores.
I would suggest making a list of some of those fish and then put it here then someone can tell you wether or not it will work out
A dwarf gourami
6 flames
4 hatchets
4 cories
6 neon tetras, 3 male guppies, 4 corydoras.
Remember, it's only a 20 gallon. Would that be overstocking?
I know, I don't think so. Hatchets have small bio loades. The DG might be pushing it but I think you'll be fine
Ok, and I have a AquaClear 50 so I think I have more than enough filtration.
And if you feel like that's over stocking, you could always go with neons
Ok, is 1 inch of fish per 1 gallon of water the rule I should follow? A clerk at PetCo said with a 20 gallon I could have 6-8 fish. I'm sure I could have more though, especially since I have a big filter.
No, nobody would put a 10 inch Oscar in a 10 gallon would you
Correct, even though while you're right, you could of said it a bit more nicely that rule is very old and shouldn't really be regarded.
Sorry, I didn't know I said it meanly. I never ment for it to sound rude.
A dwarf gourami
6 flames
4 hatchets
4 cories
Note, this a a freshwater tank, I looked up the flames and the only freshwater one I could find is a flame Dwarf Gourami