Hmmm. BG spawn once a mth. in the south during April - Aug. +- . Tilapia are mouth brooders. There are several species of tilapia. Mozambique tilapia (O. Mossambicus) being the one most discussed here.
Tilapia
Life History and Biology
http://srac.tamu.edu/tmppdfs/127565-283f...37b071f2c79794c Under
good growing conditions in ponds,
the Mozambique tilapia may reach
sexual maturity in as little as 3
months of age, when they seldom
weigh more than 2 to 4 ounces (60
to 100 grams). In poorly fertilized
ponds sexually mature Mozambique
tilapia may be as small as 1/2 ounce
(15 grams).
In all Oreochromis species the male
excavates a nest in the pond bottom
(generally in water shallower than 3
feet) and mates with several females.
After a short mating ritual the
female spawns in the nest (about
two to four eggs per gram of brood
female), the male fertilizes the eggs,
and she then holds and incubates the
eggs in her mouth (buccal cavity)
until they hatch. Fry remain in the
femaleÕs mouth through yolk sac
absorption and often seek refuge in
her mouth for several days after they
begin to feed.
AQUANIC
Maternal mouthbrooders, spawn twice a month, 2,500 eggs/lb body weight, eggs hatch in 5 to 7 days.
http://aquanic.org/publicat/state/il-in/as-494.htm My limited understanding is 14 days for the female to develop eggs + plus the spawn ,+ 7 days to hatch , + a day or 2 before expulsion from her care , then start all over. One brood every 24 to 28 days.