Sooo, I decided to spoil my two fantails with the 55 I originally wanted cichlids in. They have just been introduced to their new home and all is well so far. I have a hang on filter from their previous tank which is rated for 70 gallons, and their new canister filter is coming Monday in the mail! Which will be used in addition to the old filter. My questions are as follows: 1. Two hoods will fit on here, what size? 2. I would like to add more goldfish, how many fancys? I don't have a quarantine tank either. 3. I bought a sponge filter but don't know how to hook it up to the air pump?