Labidochromis caeruleus "Lion's Cove Yellow" or better known as "electric yellow mbuna" do not form pairs when breeding and are mouthbrooders. I keep a group of 17 electric yellows in a 55 gallon (210L) tank with 3 Neolamprologus brevis "Zaire black-fin", 1 Cynotilapia sp. "mara" male, and 1 Tropheus moorii "Kiriza Kaiser II" female. (lots of odds and ends) The tank is decorated with large rocks locally collected and large tufts of java moss. The front half of the tank is covered in crushed coral for buffering. Water is kept at 80deg F by an Ebo-Jager 200w heater. Filtration is done by a Whisper 5 and an AquaClear 200, both with foam inserts only. Tank pH hovers around 8.3, hardness around 200ppm. No ammonia, nitrites, nitrates around .25ppm (as tested with a SeaChem Nitrate kit). Weekly 10% water changes are done, 2 teaspoons of marine salt and .5 tsp of sodium bicarbonate are added per 3.5g of water changed. Stress Coat also added to dechlorinate.
I have not vented all the yellows so I don't know the exact sex ratio of the group. The largest yellows are slightly over 3" and the smallest around 2". The first female to spawn is about 2.5" in length. I first found her hiding among the rocks refusing to come out and eat with the rest of the group 4 weeks ago, obviously holding eggs. I left her in for 3 weeks, then removed her to a 5.5 gallon (20L) tank with some java moss, a small powerhead and sponge, and a heater. Here she hid for a week, refusing to eat or spit out the fry. So after a week, I stripped her and pulled out 6 very large fry, between .25 and .5" in length already. The fry were placed in a net breeder in the 5g tank and the mother remains in the 5g for recovery (heavy feeding of high protein goodies) before returning to the main tank. Fry are eagerly eating live baby brine and remarkably, already show some yellow coloration at this size. Fish in the main tank are usually only fed two kinds of food, Wardley's spirulina flake and Aquadine's spirulina formula. This is done for the well-being of the lone tropheus. The other fish don't mind the veggie diet at all and when the tropheus is holding (she still lays eggs every month oddly enough and refuses to eat for a week or so, before deciding her eggs are more useful in her stomach with no male around) I gorge the others with more normal foods like frozen brine, OSI Cichlid flake, etc..
I was unable to observe the kind of parental care associated with mouthbrooders as my female was overly-attached to her fry and stripping was done to prevent both mother and kids from starving. I attribute this behavior to inexperience as a mother (first spawn). Hopefully as more females breed and gain experience, I will be able to let them tend for their fry without intervention.