Once in a while tilapia will eat fish fry/yoy (including other tilapia) but not their own offspring. They are mouth brooders as described in the SARC fact sheet below.
SRAC 283 Tilapia: Life History and Biology http://srac.tamu.edu/tmppdfs/381285-283f...8e62d2210123f87
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
female's mouth through yolk sac
absorption and often seek refuge in
her mouth for several days after they
begin to feed.