I have a 20 gal tall tank. I want to put swordtails in it. I also want to put a pleco in there and a few corydoras catfish. How many can I comfortable have in there without crowding, and taxing the water chemistry too much??
firstly add the fish slowly, only add 4-5 small fist at a time (every two weeks or so), to allow the good bacteria time to grow.
You can hold happily about 20-25 fish but the dose change allowing filteration, aeration and surface area. Also only get a small pleco, like a bristlenose that only gets to 6", wher the commen's get to 20" and soon out grow small tanks