Depends on if you want a species only tank or if you want a community tank.
If you want species only than a male and female pair will fit nicely in a 29 gallon, but in order to accomodate for fry you shouldn't put anything else in there.
If you'd like more of a "community" tank I kept one female convict, with a red eye tetra, 2 juvenile bala sharks, and 2 chinese algae eater (when the algae eaters passed away due to a mishap with salt) I then added 3 clown loaches.
They were all in a 29 gallon, untill my sharks got to about 4 inches and I had to buy a 55 gallon. Now my convy is in the 55 gallon with all the fish mentioned above, and 2 platty's and 2 cory's.
So all and all it depends on what other kinds of fish you want. If you'd like more of a community tank, I suggest getting one female, (as the females are mellower and have bright orange coloring on their bodies when they mature.)
Hope this helped a bit! and Remember when choosing tankmates, all fish are different and you could get stuck with a much more aggressive fish than I did.
Also i don't advise putting a male and female in a 29g "community" setting, as they become extremely aggressive when rearing fry.