As a female Oreochromis produces small clutches of
eggs, commercial hatchery operators have to keep and
manage a large number of broodfish to fulfill the
demand for seed. For instance, more than 60,000working broodfish are required to produce 5–10 million
fry per month (Bhujel et al., 2001a,b). Moreover,
broodfish grow continuously even when reproducing
at a high frequency (Macintosh and Little, 1995). Bigger
fish require more feed and space and are difficult to
handle while seed harvesting; therefore, broodfish need
to be replaced frequently.