i had a male in a 10 gallon tank with 2 fancy goldfish few zebra dainos and a bamboo shrimp.... he was only mean when there was blood worms in the tank and of the goldfish got near his plant....another thing is they like to sit on top of plant semi close to the surface like bettas so they dont have to constenly swim..... if u get a female make sure that u have plenty of hideing places also if they breed the males tend to be protective of the fry like bettas but they will work out if u watch them good and take care of any aggression...