Yes definitely get more serpaes. I had bought 2 and put them in my 29 gallon a long time ago, and the next day they attacked my poor Platy so bad and started nipping pieces of fins off. We took them out and put them in a pot until we could get another small tank. We ended up getting a 26 gallon and put them in there along with 3 more of them. Then we bought 5 silver tip tetras to go along with them. They dont hurt the silver tips. Just chase them, which silver tips act the same way. The serpaes mainly chase each other. Theyre pretty, but definitely nippers and agressive in my experience.