Jack Dempsey's are not a fish that plays well with others even from quite a young age. The minimum tank size for a single Dempsey is 55 gallons/210 Litres, and keeping a pair, even a breeding pair, should not be attempted in a tank less than 75 gallons/285 Litres. Bigger is always better fish with these fish, even more so that with other cichlids. Dempsey's are highly territorial and will take their bad temper out on tankmates if they feel that their territory is being "invaded". As these fish are not enormous in size, like many other extremely territorial cichlids, the amount of damage that can be done in each attack is not as severe, but with on-going beatings on a regular basis, even the hardiest tankmate will eventually succumb. If you would like to keep your Jack Dempsey with other cichlids, then it is recommended that you start with a minimum of a 100 gallon tank and keep your fingers crossed. As with many medium to large cichlid, getting your Dempsey to co-exist with other fish, even in a large tank, can be a bit of a hit and miss experience. Due to their pugnacious nature, there are some Dempsey's that just cannot be kept with other fish, no matter the tank size or tankmates attempted. If you are going to attempt to keep you Jack Dempsey with other fish, then you should be prepared to keep a very close eye on your tank for the first few weeks and be ready to remove the other fish if aggression ensues. It really comes down to trial and error with these fish, and be ready to have many trials before you find a workable combination.
