Hi :) Yes, you can only keep one siamese fighter and it should only be kept with with Bala Shark, Chinese Algae Eater, Corydoras Catfish, Glass Catfish, GloFish, Molly, Pearl Gourami, Platy, Rainbow Shark, Red Tailed Shark, Swordtail, Three Spot Gourami, Upsidedown Catfish, Zebra Danio.