The first thing I would do , is a water change, and drop the temp to around 78, (slowly) Then, I would take half of what you have,( all if possible) to the pet store, read up on cycling, read up on the specie of fish you desire, and then, buy a tank, or buy fish that will fit in your tank. angels are not a beginners fish, they need specific water chemistry to thrive and be prolific. Sorry if That seems to forward, but thats my opinion, a twenty long, gives them no swimming room, the amount of angels you already have are enough to overstock a 55 . They need height in a tank, and a twenty long doesn't offer that.