I have a 30L x 18W x 24H 55 gallon aquarium With 2 Marineland Penguin 200 filters. The tank currently has a few tropical fish in it. How many Fancy Goldfish could I keep in it once the tropical fish are gone? I also want a few plants, but Im not sure what kinds to keep with goldfish. What sort of Fancy Goldfish are best with each other?