55 gallons is a great size to start out with. I'd aim for 12 adults, 3 species of 4 each (1m/3f).
electric yellow labs, or
labidochromis caeruleus, is an excellent species and IMO all mbuna keeper should have them at least once. They are peaceful (for mbuna that is), but mix well with aggressive species. They are peaceful enough to be able to keep multiple males, which is fortunate as they are difficult to sex.
Johanni,
melanochromis johanni are an aggressive species that IMO shouldn't be kept in anything smaller than 75gal.
Kenyi,
metriaclima lombardoi, same as johanni
Demason's cichlids,
pseudotropheus demasoni, another excellent species, they are extremely aggressive toward their own kind, but will ignore other fish that don't look similar. Because of their conspecific aggression, they should be kept in groups of 12+, or just a single specimen. They are a classic pairing with
l.caeruleus, and because they are small, you could keep 12
p.demasoni with
5 l.caeruleus quite happily.
Here's a link to more suggestions:
[URL="http
/www.cichlid-forum.com/articles/cookie_cutter_55g.php"]http
/www.cichlid-forum.com/articles/cookie_cutter_55g.php[/URL]
I recommend going to your lfs and writing down all the names of the fish that interest you, then research them and posting on here for stocking and compatibility help. You're doing great so far!
The best advice I can give with mbuna is to research, research, research. Never impulse buy a fish without knowing what it is, that's just general good advice, but is doubly important with mbuna as that cute little fry could turn into a killing machine. Also, never buy from the "Mixed African Tank", or "Malawi Community tank" as most of those fish are hybrids, and a fish with unknown parentage isn't a good idea.