Provided the tank is large enough and the fish are of a similar size there should be no proplems until a couple pair off and decide to breed. Then, if you don't have the facilities to house either the breeding pair or the other fish you will have problems. The basic rules for keeping any kind of fish successfully are :- 1 inch of fish needs at least 1 gallon of water.(2 Jack Dempseys need at least a 30 gallon tank.) :- Every tank needs a permanently running cycled filter. :- Every tank needs at least 50% of its water changed every week. Jack Dempseys are tropical so they will also need a heater/thermostat set at around 78F and a thermometer so that you can check the temperature daily. They also need to be fed morning and evening as much Cichlid food as they can eat in 15 minutes. No food should ever be left to rot in the tank because it will poison the water. If you follow the above guidelines your fish should survive OK. If you fail in any of the requirements above I can guarantee that your fish will be constantly getting sick and will live a shortened lifespan..
Jack McKeon goes by Trader Jack.
Jack Brabham goes by Black Jack.
Jack Struller goes by Crazy Jack.
Jack Coombs went by Colby Jack.
Jack Freiburg goes by Uncle Jack.
Jack Cruikshank goes by Jack the Gripper.
Jack Brosseit goes by Action Jack.
Jack Pennington goes by Whiny, and Jack.
Jack Mower went by Jack Mower.
Jack Manders went by Automatic Jack.
Jack Hanna goes by Jungle Jack.
Jack De Sena goes by Jack.