There is a thread on one of these forums with pic's of a JD/convict hybrid somewhere and as for sexing the try and look for larger fish, the males have pointed dorsal fins and females have rounder dorsal fins.
Worth a try but there's still the risk. You'll need another tank just in case.hmmmm what do you think about a female dempsey for him?i just dont want him to be all by himself in a big tank wouldnt it get boring/lonely?
Convicts are touth little fish that are more than capable of looking after them selves. If you put a female in it is possible they would breed and then you'll have some cool convict/JD hybrid fry.
The convict would be a better choice, the salvini would probably kill the jack in a smaller tank like yours.
salvini's are overrated!the one i had would get beat up by everyone and he was bigger then them.