All the comments on this page are true, they are very aggressive! But I just love my little male Midas. He is only 10 cm long, and already he bites my hand while cleaning the tank! He jumps out of water for food, and is very active. A Midas is a must-own cichlid for any cichlid lover, as it is packed with personality, and will bring you years of enjoyment.
I must agree about this fish's aggression. My 9 year old adult male more or less cleared out the other residents of my 760 L tank, even killing a 30 cm long pleco. He is really like an aquatic puppy, though. Pandering for food, "kissing" the glass, and following you around. The only other fish left alive in the tank is, believe it or not, a 8-10 cm Steatocranus casuarius, or "buffalo-head" cichlid. They have been tankmates for over 5 years, and the midas has more or less "adopted" the little guy as his brother. In fact, the Steatocranus bites and harasses the Midas, and not vice versa. In summation, these fish are certainly best kept alone. Mixing other species with them will usually result in an unpleasant ending.
I have a 9 year old Midas Cichlid who is about 30 cm long in a 300 liter tank. She'll kill any other fish we put in the tank and attack your fingers through the glass, but put your hand in and she cuddles up. After a few minutes of affectionate belly rubbing she turns pink and calms right down. I even pick her out of the water where she lies in my hand for a few seconds before flicking her tail and sliding off. The only time she gets aggressive is when you try to leave, when she bangs the glass and goes dark. She has really become a part of the family and I feel is much more intelligent than a lot of people give credit. Perhaps the reason so many are aggressive is they're intelligent and bored.
There are instances for midas and even a red devils to coexist with other tankmates. One of the ways is to have many target fish, such as convicts. I use convicts in my tank with 4 of my barred midas and 4 of my devils and about 8 convicts, none of them has a torn fin or a missing scale, but in order to maintain these conditions you must work with the fishes from a lot of angles and have to put a lot of work in the aquarium.
In one tank I have a Midas along with a Texas Blue, Firemouth, Green Terror, Jack Dempsey and one huge Oscar. To my suprise, in the three years they have been together they have all grown together and gotten along quite well. I have never fed them live food. I substitute with frozen food and a healthy portion of pellets. Like my grandfather said, they did not become competitive for food, and that is what I credit my success to. In fact, they all seem to like to hide behind the oscar when it comes time to clean the tank! Thanks Grandpa.
This is without a doubt my favorite fish! I've been told that other people have been able to keep these guys with other fish, but all my attempts have been met with disaster, so I keep my guy Bubba all alone. It is an adventure with him at tank cleaning time, as he has taken a liking to the taste of my hand. I will never go without a Midas as long as I have a tank!