Tilapia Cage Culture(Part 1)

Tilapia are sometimes known as “aquatic chicken”, due to their high growth rates, adaptability to a wide range of environmental conditions, ability to grow and reproduce in captivity and feed on low trophic levels. As a result, these fishes have become excellent candidates for aquaculture, especially in tropical and subtropical regions. Indeed, tilapia culture has been expanding rapidly, and is now practiced in more than one hundred countries worldwide.
Tilapia cage culture is growing tilapia in cages made of nylon nettings and bamboo frames that are floated, submerged or fixed at the bottom. It utilizes bodies of water such as dams, rivers, lakes, bays, reservoirs and coves. This is one of the effective technologies used in raising tilapia. It started out in 1974 in Sampaloc Lake and Laguna Bay and being practiced now in different regions like in Magat Dam Reservoir in Region II.
The following are the advantages of tilapia cage culture:
• easier handling, inventory and harvesting of fish

• better control of fish population

• efficient control of fish competitors and predators

• effective use of fish feeds

• reduced mortality

• high stocking rate

• total harvesting and swift or immediate return of investment

• less manpower requirement

• minimum supervision
There are two types of cage design — fixed and floating. The fixed cage is suitable with a water depth of 1 to 5 meters and the usual size is 50 to 200 square meters.
The floating fish cage, on the other hand is from 5 meters deep and about 50 x 25 x 3 cubic meters depending on the area where the fish cage is placed. It is supported at the bottom with a stone weighing 40 to 100 kilos and covered with a net to prevent the fishes to escape.
The success of the project depends on the quality of breeds or species of fish as well as the production capability of the selected site in enhancing the maximum growth of the fish. Tilapia species is widely used as fish stock because it grows fast. It takes only four months for fingerlings to reach an average weight of 100 grams.
Site SelectionWater circulation.

The Magat Dam has water current circulation throughout the area that gives a continuous flushing of water inside the cages, making dissolved oxygen highly available to fish and wash out metabolites. Wind direction from northeast to southeast or vice versa prevails in the months of March to August. The prevailing winds augment the distribution of natural fish food within the dam.
Protection from winds and waves. Locate the site in waters protected from strong wind action and water currents caused by flush flood or heavy runoff. In the Magat Dam, there are few floating debris; the quantity increases as the wind changes its direction and force. However, this could be checked by providing floating bamboo barricades or wave breakers facing the direction of the wind.
Dissolved oxygen concentration. The ideal range of dissolved oxygen concentration on the water must be at least 3 ppm (parts per million). For tilapia, a lesser ppm is not considered lethal. However, growth and reproduction is greatly affected.
Temperature. This is one factor that plays a major role in the growth of the fish stock. The suggested range is from 20°C to 30°C. The lethal temperature levels are 12°C and 42°C.
Pollution. The fish-farmer should know the effect of thermal, biological and chemical pollutants to the fish stock which may come from domestic, industrial and agricultural sources. pH Level. To enhance a better growth, the recommended pH range is 6.8 to 8.0.
Accessibility. The site must be accessible to land and water transportation to facilitate bringing in of inputs and marketing of produce.
Other factors. One social problem existing in any fishery establishment is poaching. Poachers get into the project at night, bore hole on nettings to let the stock escape, then set gill net on surroundings of the project. This gives a bountiful catch overnight. This problem can be remedied by the management by establishing good public relation with the people in the vicinity. Another consideration is the source of fingerlings for periodic stocking.
Structural Design and Construction of CagesThe design of fish cages is determined by the behavior of the culture species. For Tilapia nilotica, which is less active and sometimes territorial in habitat, the shape of the cage does not affect its mobility. In this case, design rectangular cages for easy assemblage and management. The arrangement of the cages is not a problem if there are only few of these. However, 8 or more should be arranged depending upon the direction of the wind.
There are many kinds of nets that could be used for cage fabrication. The most common are the B-net (1/4? mesh), DD-net (3/8? mesh) and CC-net (1/2# mesh). However, the most popular is the B-net because smaller fingerlings do not need a nursery cage. It is cheaper per unit area because it is wider (108 inches) than other nets, hence, labor cost in fabricating cages is much lower, and tearing of one or two meshes do not easily provide an escape route for bigger fish.
Generally, floating net fish cages are made of nylon nettings supported on all sides and corners with polyethelyne rope fixed by a nylon twine. Each is hung within a rectangular area, the top is supported by bamboo braces and the bottom is provided with lead sinkers. The size of net cages used in Magat Dam for commercial production of tilapia is 6 m deep, 6 m wide and 12 m long. This size makes possible the full utilization of bamboo poles and nets. To do it, hang the net cages in bamboo raft type frame which also serve as catwalk for workers allowing 1 m of the net above the water level and fix the synthetic ropes to four corners of the poles to prevent the fish from escaping by jumping out. The longest side of the cages is oriented perpendicular to the direction of the wind.
Construct the net fish cages in the following manner:
* Cut the net according to desired specification

* Double-lace every mesh of the four corners using nylon twine 210 d/6, double-twine beginning at the second mesh row using rolling hitch or clove hitch with a single hitch as lock at intervals of 7.62 - 10.16 cm.

* Double-lace the nylon salvage net to the top edges of the cage with a nylon twine, using either a rolling hitch or clove hitch with single hitch as lock. Start the second half from the second mesh row.

* Rig all sinkers (No. 7) to the rib lines of the bottom side and centers. Attach the rib lines on all sides using rolling or rib hitch with an interval of 7.62 - 10.16 cm.

* Make splices on the four corners of the hanging lines (top portion of net cage) for the attachment of four stretching ropes with weight. Continue with the other units following the same procedure.

From Jeepney Driver to A Successful Farmer

Diligence, foresight and determination to provide well for his family were the key factors that led Rodolfo “Ronnie” Abas, 57, to success.
Forty-two years ago, he was just a mere jeepney driver who was earning what was left from his P8-boundary. Now he cultivates more than 100 hectares (has) in Kiliog, Libona, Bukidnon. His farm is planted mostly to corn and raises 110,000 broilers per growing cycle with the help of his son Marte, second in a brood of five.
His wife of 39 years, Mila, a former high school teacher, has provided him all the assistance he needed from a loving wife.
Ronnie, a high school graduate, narrates that he became jobless for a year after he got married. The owner sold the jeepney that he was driving, and he was forced to stay at home doing nothing but to take care of their firstborn child.
He was mad at himself very often because his wife was the one canning. He also found it difficult to be a”taynaylong” (a term coined to describe a person who acts as tatay [dad], nanay [mom] and katulong [househelp]). Much as he wanted to be the breadwinner, he could not find any profitable job. And he was worried of what could happen if he Would have more children.
JUNKED JEEPNEY FOR A STARTEven with his predicament, Ronnie envisioned himself to be the owner of a fleet of jeepneys.
And by the stroke of fate, probably, he found in 1970-a junked jeepney for sale. His problem, of course, was that he did not have money to buy it. He needed P 10,000 to buy it even if its engine was no longer functional and its tires needed replacement. His last recourse was his aunt who, upon learning of his only opportunity to become a family breadwinner, bravely lent him money.
“Because of my happiness, I really cried when she gave me the money,” Ronnie said.
After repairing the engine and vulcanizing the tires, he started to use the vehicle to ferry passengers from Libona to Cagayan de Oro City. In one particular trip, he was hailed by pregnant woman who wanted to be brought to a hospital in the city. He initially refused to take her, thinking that it would be bad luck for him and for his jeepney if she died on the way to the hospital.
But he it did not take him long, when he thought that his conscience would be greatly bothered if the woman died for not being brought to the hospital; so he backed up to get her. As he was traversing the very rough road down to the city, the woman already gave birth. This made him increase his speed, not minding his jeep’s worn out tires.
When he visited her the following day, he found out that she needed some money to pay for the hospital bill. Without even thinking twice, he gave her P50, the only money in his pocket. Ronnie said this particular event was the turning point in his life.
The following day was the feast of the Virgin Mary, the patron saint of Brgy. San Miguel, Manolo Fortich, Bukidnon, which is adjacent to Libona. Just like any other barangays fiesta in the Philippines, people from other barangays attended the fiesta. Much to Ronnie’s delight and astonishment, it was his jeepney that was loaded with passengers all the time. Passengers insisted to ride in his vehicle even if it was already loaded to the brim, so to speak.
From then on, his income from the jeepney kept on increasing. Not long after the acquisition of the first jeepney, he decided to loan from a bank to buy another jeepney. One loan after another led to the development of a fleet of more than 10 jeepneys.
TRIES AGRICULTURAL LANDSHis success in running a jeepney fleet did not make him complacent. Instead, he decided to try his luck in agriculture.
That is why even if his first jeepney has some sentimental value, he sold it for P70,000 in 1982 to buy 6 has in the town proper. However, the land was adjacent to the residential area and Ronnie thought it would be extremely difficult for him to expand the property if ever he would have money.
He sold the property a year after for P230,000 and bought 5 has in Kiliog for P75,000. He also bought six cattle for draft purposes and used the rest of the money for mortgaging lands from neighboring farmers and for production inputs.
For a start, he had 10 has planted to corn. Even if his harvest was low and the price of corn at that time was only P2 a kilo, Ronnie was making money from his agricultural venture.
Not long after, he bought again 7 has for P70,000. He realized that he was making more money from agriculture and, hence, decided to sell his passenger vehicles to be able to further expand his agricultural operation.
By 1990 he already owned 20 has and he decided to mechanize his farming operations, as he could no longer rely on animal power for land cultivation. Thus, he obtained a loan of P700,000 from the Land Bank of the Philippines (LBP) to buy 90 hp Ford 6610; he also borrowed P200,000 for production cost.
Unfortunately, the crop failed because the rains stopped after two downpours. Although he paid the premium for the insurance of his crop, the Philippine Crop Insurance Corporation did not pay for his losses worth P 100,000 because the bank failed to remit the premium.
The best thing he got from LBP was a restructuring of his loan amounting to P100,000, as this was the amount that he actually spent. The next crops were successful and so he was able to pay his loans.
Ronnie said his success in corn production is primarily due to the use of hybrid seeds and Bt corn, which is resistant to the destructive corn borer. Among the varieties he is using are Dekalb and YieldGard, which are marketed by Monsanto Philippines.’ He said he has used hybrid seeds of San Miguel Corporation, Ayala and Cargill.
He mentioned that his corn yield is normally higher in the first crop with 9 to 10 tons a hectare (t/ha). Although the yield of the second crop drops to 5 to 6 t/ha, it is compensated by a much higher price and, hence, still makes almost the same net income as from the first crop.
For this cropping season, he has planned to try Durabloom, a bio-organic fertilizer produced by Novatech Agri-Food Industries, in a few hectares in an attempt to cut down fertilizer cost. The rains had not yet come when we visited Ronnie last April, but the fields were already ready for planting as soon as there is enough moisture in the soil.
He said that although farmers in other parts of Mindanao have already successfully used Durabloom, he has to try it himself before using it on a wide scale. “We’ve got to go slow on this,” he said. “If I find that it (Durabloom) works well, there will be no reason why I will not use it on a large scale.”
As a large-scale corn producer, he has already mechanized his farm operations. Lately, in a trip to Thailand with his family, he brought home a 4-row corn planter, which he bought for P200,000. For faster land preparation, he has also acquired three large tractors.
He said, however, the corn harvest must be dried soon after harvest so that the grains would not be attacked by aflatoxin, a fungus that diminishes the quality of the grains. If the corn would be free from the fungus, he could sell his produce at good prices. He invested P1 million for the installation of two vertical mechanical dryers right in the farm.
To insure availability of water for his crops, he installed three years ago several deep wells (248 feet deep) in strategic locations of the farm.
BROILER PRODUCTIONNot yet contented with his success in corn production, he ventured into broiler contract growing with Swift RFM in 1994. For a start, he had three broiler houses with a capacity of 10,000 birds per house.
Ronnie confessed that he was so excited with his new venture because it was his first time to see and take care of such a large number of chicks. Although he really did not know much about broiler production, he had to learn all the tricks as fast as he could. Indeed, determination and diligence made him a successful poultry grower.
After 13 years, he now has nine poultry houses with a total capacity of 110,000birds. Four houses can contain 15,000 birds each, while the five other houses have a capacity of 10,000 birds.
Marte, a nursing undergraduate, now manages the poultry business. He said they have five to six production cycles a year. After 13 years with Swift, they recently decided to do business with Gamma Fanns, a supplier of birds for the roasted chicken business.
Marte also manages the poultry farms of his uncle and another grower. All in all, he raises 540,000 birds per grow.
BACK TO JEEPNEYS, THEN HAULING TRUCKSEven if Ronnie sold his fleet of passenger jeeps earlier, he was forced to buy a brand new Armak passenger jeepney in 1989 because it was already becoming difficult for their children to get a ride to school. Besides, he was still the president of the local jeepney operators and drivers association, a position he held for 20 years.
By 1997, he already had 12 Armak passenger jeepneys, as he continued to buy one after another whenever he had extra money.
Later, he bought a truck with a capacity of 18 tons, which he used for hauling pineapple on a contract basis for Del Monte, which is adjacent to Libona. He was attracted by the handsome income and, hence, decided to sell the jeepneys to buy three more trucks.
Lately, however, Del Monte decided to hire 10-wheelers only. Because the income is good, he had his hauling trucks converted as such to conform to the demand of the pineapple company.
Ronnie is a kind of person who catches every opportunity where he sees good income. It was only recently that he also became a contract grower of Del Monte; he allotted 2 has of land - near his house - for this purpose. Del Monte provides the seed pieces and fertilizer, while he provides the labor.
He said he can harvest three times from one crop. The first harvest is done 18 months after planting. This is followed by a second harvest nine months after and a third harvest after another nine months.
The income is attractive as Del Monte pays P3 a kilo for the first harvest and P1.75 a kilo for the succeeding harvests. Ronnie said the cost of production for the first year is P147,000 per hectare.
Ronnie has also allocated a portion of his farm for fruit production. Although he says that it is not on a commercial scale, he has more than 600 fruit bearing trees of durian, over 200 lanzones, 35 pummelo, several mango trees, and lots of lakatan banana.
Ronnie has not yet stopped looking for business opportunities. Aside from his ventures in agriculture, he also has a fleet of 52 taxis in Cagayan de Oro with the name Abas Farm Taxi.