Red Medium

Red Medium
Are there any other type of fish you can suggest to put in my tank with my medium-sized enterprises Red Devil?

I can not even algae to eat 3 times Red Devil size in that country.

Once a fish like a red devil decides that the whole area of the tank is his territory, then he would never allow anything else that inhabit it. The only thing I could suggest is similar to another suggestion. Get a larger tank, 100 g minimum, bigger is better. Get It bike with some fish expendable, and then put it there with other similar fish aggression. It should have enough room in something bigger to demarcate territories without killing each other.