I just got a fish tank yesterday and I set it up. I would want to find out about this because I really dont want to have alot of fish that wont work together. I am also wondering if you can put angel fish in a 20 gallen tank, and how many and with what fish? I want a group of selected fish like more then one kind of fish. Make sure they can be placed in a tank together. I have a filtered tank which is fresh water. I would like a possible awnser soon as possible! Thanks!