it depends on the tank size you have.
Neither of mine are agressive, They dont care about feeders or really anything other than massivore pellets or an occasional freeze dried krill.
oh and The death toll from both of them over the last 8-10 months ive had them is 2 convicts and one buttikoferi.
the dead were all under 3" and it was in a 30gallon grow out (for each at seperate times)
Piece of advice that every newbie seems to need to be told (don't worry, we all did it!); do the research BEFORE buying the fish, not after.
There's a million different websites with species profiles that will tell you all about the water, temperature, feeding, aggression etc of the species you're interested in keeping. Five minutes worth of googling before you went to the LFS would have told you the fish you have aren't compatible with a jag....