What would go good with my 4 Kuhli Loaches in a 20 GAL?

I have given my goldfish to a better home (I don't have room to supply to the needs of goldfish as I thankfully found out soon enough!) and I wanted to keep my 4 Kuhli loaches in my 20 GAL tank and was wondering what types of fish would be good? My boyfriend suggested a plecostemus (Sorry I don't know how to spell it!!) But I don't think that'd be good considering they get to be just as big as goldfish from what I've seen! Also, I have three male tequila sunrise guppies and was wondering if they would be alright to put with the kuhlis? Also, what else could I add? I really wanted to put six female guppies with them, because I know that male guppies need twice as many females with them to live peacefully!! ^____^ PLEEEEEASE help me!

 

Guppies would be fine. The only thing about mixing males & females is they breed like rabbits and you could eventually end up overstocked. If it were me, I'd probably just add more male guppies (maybe about 5 more). That would make a nice, active, colorful tank.

-Chelle