I'll start us out, I kept
L.caeruleus for a little over 3 years. I found them to be a fantastic starter mbuna species as they are quite peaceful compared to the majority of the species.
That said, I started with several in a 29 gallon bowfront tank and soon 1 male and 2 females took over the tank killing all of the other occupants. They bred several times and would even kill their offspring once they reached around an inch. About a year after I started the tank I upgraded to a 75 gallon and after adding the adult labs with juveniles of several other species the labs quickly became quite docile and dropped to the bottom of the hierarchy.
IME they are far less shy when kept in groups of 5 or more, when kept in an adequate sized tank (4ft) multiple males are tolerated and oddly enough even the most aggressive species tend to ignore them. They are one of the few omnivorous species mostly eating insects and small crustaceans in the wild. As such they tend to ignore most vegetables but
love the occasional brine shrimp treat or small snails (ie. malaysian trumpet snails).
They can be mixed with peacocks and haps as well due to their more peaceful temperment and feeding requirements.
All in all I highly recommend them to anyone interesting in mbuna, new keeper and experienced alike.
Here are a few pictures of my past labs.
Holding female
Male
Female I believe
Male I believe