BG and LMB can cross with viable offspring. I have seen pics but that is not one on that site.

Here is some info on Oreochromis reproduction.

http://srac.tamu.edu/getfile.cfm?pubid=53

SRAC 0283 Tilapia: Life History and Biology

Reproduction
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.
Sexual maturity in tilapia is a function
of age, size and environmental
conditions. The Mozambique tilapia reaches sexual maturity at a smaller
size and younger age than the Nile
and Blue tilapias. Tilapia populations
in large lakes mature at a later
age and larger size than the same
species raised in small farm ponds.
For example, the Nile tilapia
matures at about 10 to 12 months
and 3/4 to 1 pound (350 to 500
grams) in several East African lakes.
Under good growth conditions this
same species will reach sexual maturity
in farm ponds at an age of 5 to
6 months and 5 to 7 ounces (150 to
200 grams). When growth is slow,
sexual maturity in Nile tilapia is
delayed a month or two but stunted
fish may spawn at a weight of less
than 1 ounce (20 grams). 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).