Hi, I currently have a 10 g. tank and I am looking to get a 20 maybe 30 gallon tank. I prefer to get a 20. I currently have 2 Albino Aeneus Cory Cats. I love the Red/Calico Fantail Goldfish and I love guppy's! I want to get 1 Fantail Goldfish, but I want to know if it would be okay to put guppy's in with the goldfish and if so how many?