55 Gal

[steven78]

Hi

I have a 55 gal tank with an undergravel filter as well as a HOB filter

was thinking of keeping glofish, neons and guppies but not sure how many of each i should get, also not sure on to get a couple of catfish or not some advice would be wonderful

also how to i know if my undergravel filter is working properly and should i leave it or turn it into a reverse UGF

thanks in advance