Steamed, grilled, fried, or mixed with a sauce, tilapia is a common type of fish used in various dishes around the world. This is because tilapia is easily grown in ponds and can be harvested after two to three months.
Tilapia is the most commonly cultivated freshwater fish in the Philippines. According to an informative brochure from the Philippine Council for Research in Agriculture, Aquatic and Natural Resources (DOST-PCAARRD) of the Ministry of Science and Technology, in addition to ponds like “Hapas” or inverted mosquito nets, the fish is also grown in other media and concrete tanks.
There are two types of tilapia in the country: the Nile tilapia (Oreochromis niloticus), which is found in freshwater, and the Mozambique tilapia (O. mossambicus), which is grown in brackish water.
Freshwater tilapia culture
One way to grow tilapia in fresh water is through cage culture, an aquaculture production system in which fish are kept in floating net pens.
Cages are usually made of synthetic netting suspended from a floating frame or attached to a structure implanted in the bottom of a body of water. The size of the cages varies between one and a thousand square meters and the depths between one and five meters.
Suitable locations for cage culture are freshwater bodies such as lakes, ponds, rivers and reservoirs, provided these locations have sufficient quantities and good water quality. Rivers should also have slow to moderate water currents so the fish don’t swim against them.
Tilapia is handy for growing over cage cultures as it tolerates crowds and lives on natural foods
such as plankton and artificial feed.
There are two basic requirements in cage culture: on the one hand, enough water should be exchanged through the cage to replenish oxygen and remove waste, and on the other hand, the fish should be supplied with food that comes from the water or can be fed to them .
However, the most important factors in cage culture production of tilapia are the size and depth of the cage, the mesh of the net and the size of the finger cots.
A smaller cage, one cubic meter in size, can hold around 250 to 400 fish in an area of 100 square meters. The cage can only hold 30 to 50 fish per square meter. This is because as the size of the cage increases, the surface area for water exchange decreases.
The mesh size of the net should also be large enough to promote water exchange, and the depth of the cage should not be more than two meters, especially in shallow lakes and rivers.
In addition, stocking larger finger cots in the cage promotes faster growth, and stocking only male tilapia improves growth, feed conversion and survival, as these develop faster than the female.
Brackish water culture
The Philippines has more than 500,000 acres of brackish ponds, rivers and bays. Commonly, the species that are cultivated in these types of water include milk fish (Bangus), shrimp and tilapia.
Brackish water has a higher salt content than fresh water.
For tilapia culture in brackish water, tilapia finger cots can be stored in an area of one to two square meters for extensive cultivation, while four to five square meters with a depth of 0.3 to 1 meter can be used for intensive cultivation.
According to the PCAARRD brochure, the Nile tilapia can only tolerate brackish water with a salt content of up to 25 per thousand (ppt), while the Mozambique tilapia can process up to 40 ppt.
A hybrid of the two species is said to withstand a salinity of up to 32 ppt or pure sea water.
Cage culture can also be used in brackish water, although site selection plays an important role. Rivers and waterways should have a minimum depth of 1.5 meters at low tide with slow to moderate currents and good water quality. The size of the cages can vary between one and four square meters.
To access the Tilapia Culture Brochure, visit the PCAARRD e-Library.
For more information on agriculture and horticulture, please visit Agriculture.com.ph.
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