Because both your cichlids are mbuna type it'd be best to get other mbuna, if instead you'd get peacock types, the mbuna will probably tear them to shreds.
Mbuna need the company of the mbuna and are generally considered quite aggressive, especially in small tanks.
A 20 gal is OK as a temporary aquarium for mbuna when they are small, but the tank is much too small for them long term, no matter how many gallons the filter is rated for.
A 75 gal tank would be more appropriate.
Mbuna need the company of the mbuna and are generally considered quite aggressive, especially in small tanks.
A 20 gal is OK as a temporary aquarium for mbuna when they are small, but the tank is much too small for them long term, no matter how many gallons the filter is rated for.
A 75 gal tank would be more appropriate.