In a word - YES.
When placing three different species, substrate spawning Cichlids together in an aquarium - you run the risk of unintentional pairing off and spawning (esp. if one of those Cichlids is Amatitlania - a Convict). A dead, non-paired Cichlid could easily result from an unexpected spawning run like that. Or, a tank just chock-full of hybrid Cichlids that no one will want.
To avoid that problem, I recommend stocking with either an all-male (Three Amigos) or all-female (Three Signorina's) stocking scheme. You'll have much less aggression in an aquarium set up like that. And, with a four foot long tank, you could probably add another small to mid-size Cichlid to that group.
NOTE: decorating with empty tequila and beer bottles for the 'Three Amigos' Cichlid stocking scheme is entirely optional, but could be scheme appropriate in depicting that happening bachelor Cichlid lifestyle in your aquarium.
The problem acquiring small juvenile fish (usually 1-2 inches) is most local fish stores and online stores do not distinguish or provide sex of fish to customers. So unless your a good judge of sexing fish you will not be able to determine until they are close to maturity or breeding age....lol....Will be interesting to see which species will be the tank boss.