no, my friend had 3 in an 8 gallon cube, they are a bit territorial but they have small territories and don't fight that much so she could probably have 6-8 in a 20 that has cover, they are reasonably cheap up here in canada, around 3-4 bucks each
they breed pretty easily in captivity and american money is worth more then canadian money so if anything it would be a bit cheaper for you, assuming you find them
also found this on aquabid, 36 bucks for 6 gudgeons, so 6 bucks each
Guppies don't do well with fast moving fish like Tetras, or anything that would nip fins, like some tetras do. My fiance has his gups in a species tank with 2 cories to clean up. Buying her a tank isn't going to get you out of the friendzone though, keep that in mind while you're going nuts here lol. I'd stick with the tetras for shiny/glittery. Good luck.
the gudgeons are the best glittery purplish colourful fish for a 10 or 20 that would allow for other fish i could think of, though electric blue rams or other cichlids would have better colour tankmates would be harder to find
I already have the tank I'm not buying it I'm just getting the stuff and I know once your in friendzone u never come out so that out of question but I'm still setting up the tank anyway but anyway she hasn't texted me back about the gudgeons she has training but what about diamond tetras they look glittery