Its just two fish though.1 male, 1 female.
A few points.
1) Cichlids are often difficult to sex reliably. There are some general indicators (body shape, fin shape, minor colour differences); but it's not 100%
2) A male plus a female does not a pair make. There are no guarantees that they'll like each other.
3) The caresheet I linked to suggests something half again as long as a standard 15 gallon for a pair (although it does mention you could go a little bit smaller for a breeding pair). When you throw it into
AqAdvisor it tosses back bunch of warnings. Both of these jibe pretty well with my gut feeling of this probably not being a good idea.
4) As a general rule of thumb, you *really* don't want to crowd most cichlid species (excluding East Africans). They're a bit fighty at the best of times.
All in all, lots of opportunities for Murphy's law here. If it were me I'd be a lot more comfortable with a 40 gallon breeder.