Hey, I'm a new user, just got a 20 gallon tank. All I have in it right now are penguin tetras and gold tetras, probably going to get a lemon tetra and a blue paradise gourami. Would the gourami have any problems with the tetras?
First off, welcome to AC!
Paradise fish can be pretty aggressive, but I don't think it would be a huge deal with tetras. By adding a lemon tetra, did you mean just 1? Tetras are schooling fish and do best in groups of 6+. I don't think your tank would be big enough for a third group of tetras though. How many penguins and golds do you have?