It would be better in a 36-inch tank. Six inches more may not seem like much, but it is to the fish.
First issue is their aggression toward each other; between spawnings Bolivian Ram
can be very nasty to each other. My male killed the female, and they were in a 5-foot 115g tank, but she could not completely get away from him. This is where the 3-foot tank recommendation comes in, for the rams themselves. They live in isolation in the wild, except when spawning, so they need space. You can read more in our profile, click on the shaded name.
As for other fish, the Ram are, like all cichlids, protective of their eggs and fry. With other fish in the tank, depending upon the traits of the particular rams, and the other tetra species, they may or may not be trouble. If you have any catfish, corys, pleco, whatever, they will almost certainly get the fry if not the eggs at night.
Unless you want to spawn them, this is an excellent cichlid to have as a solitary fish in a community tank, and a 29g is fine. Have some bogwood, this fish likes to be able to get out of sight now and then, or it will not feel secure.