If you have a small land platform you could try a Green Frog. I had one in with some swordtails and a
goldfish for quite some time. They all did great together. Just don't put them in with slow moving fish like Bettas (poor
betta got de-finned). The occasional guppy might disappear, but the frog's comical behavior more than makes up for it. make sure you have a well fitting lid because I didn't and I found mine shriveled up behind the couch still alive. If it does get out and it's still breathing just float him in a fishnet so that the fish can't pick at him. He'll eventually re-inflate and swim around again.