er...i know its over stocked but....
in my 5g, i have a male vt, 2 cory cats, and about 5-10ish snails....and its been like that for about 2ish-3ish months now, and their doing great. Just when introducing anything to a betta in a 5g tank, make sure you are hawkeyeing it for the first hour or so, because there isnt alot of swimming room for anything to escape the betta if things do go bad.
EDIT: And yes, the snails are 90% of the water pollution, because i sware they are pooping 24/7
Mine and MichelleLouise's betta list:
-(RIP) Pablito: VT male
-Pablito Again: VT male
-Pippins: CT male
-Clifford: CT male
-The Peacock: CT male
-Dotty: CT male
-Juno: CT female
-Gryxi: CT female