I agree with everything liv2padl said.
Yes, all three species are Malawi. No, not all mbuna (which you have) need to be kept in groups of four. This is a general rule and works for most mbuna. IMO The Melanochromis johannii, and the Pseudotropheus socolofi are best at 1M/3F......and the Labidochromis caeruleus like to be in groups of 5-7. The male/female ratio on the labs are not as critical as other mbuna. Another option would be to keep one of each of the three species you have, but they are happiest in groups.
I cannot stress enough, Malawi cichlids do not belong in a small tank. They will be very unhappy and you'll end up with one fish in the end. As liv2padl said, 55g minimum, or I would choose a different type of fish to keep.
Also, even though Malawi cichlids are highly aggressive, don't be tempted to feed them any protein or feeder fish. They are strictly vegetarians. Feeders and high protein foods will kill them.