Harvesting and marketing
Harvesting schedules in tilapia culture depend very much on the seed stock used and the climatic conditions in the area. If exclusively mono-sex males are cultured in tropical climates, the duration of rearing can be adjusted according to the preferred size to be marketed. If unsorted stocks are used, or if the hybrids or sorted stock include some females, harvesting is generally carried out before too much wild spawning has occurred.
When ponds and rice fields can be drained, fish harvesting presents few problems. Harvesting from cages is also fairly easy. Partial harvesting in ponds is generally by seines, but significant differences in catchability have been observed between species and hybrids. T. hornorum is a species that can be caught easily,whereas T. nilotica and T. aurea avoid seines by lying on their side on the pond bottom. and repeated seinings are necessary to catch a good proportion of the stock. Catching becomes a major problem in pen culture as indicated. All-male hybrids of T. nilotica x T. hornorum are reported to be caught muchmore easily from ponds.
In small-scale rural farms, the marketable surplus catches are generally sold fresh at the farm gate or in the nearby village markets. Larger farms usually transport the catches to urban markets on ice, and in the case of far away markets somttimes even frozen. In markets where tilapia is not a favoured fish, it has often to be presented in a value-added form under a different name. The demand for red-coloured mutant tilapia was mainly due to the fact that fillets of the fish could be sold under a different name (fresh-water snapper). Cans of processed tilapia have been produced on a limited scale in some countries like Costa Rica. Experience in a number of developing countries, where tilapia have been introduced, seems to show that markets can be developed if fish of at least 200–250 g can be sold at a competitive price. Larger fish of 300–400 g size attract more consumers. The market that has developed in the Philippines for tilapia since the 1970s is illustrative of this.