Tilapia Farming and Tips

Tilapia is the common name used for a variety of cichlid fishes of the genera Oreochromis, Sarotherodon, and Tilapia. Tilapias inhabit a variety of fresh and, less commonly, brackish water habitats from shallow streams and ponds through to rivers, lakes, and estuaries. Most tilapias are omnivorous with a preference for soft aquatic vegetation and detritus.

Because of their large size, good flavour, and rapid growth rate, many tilapias are at the focus of major fishing and aquaculture efforts. Set against their value as food, tilapias have acquired notoriety as being among the most serious invasive species in many subtropical and tropical parts of the world. For example Oreochromis aureus, Oreochromis mossambicus, Sarotherodon melanotheron melanotheron, Tilapia mariae, and Tilapia zilli have all become established in the southern United States, particularly in Florida and Texas.

Apart from the very few species found in the Levant, such as Sarotherodon galilaeus galilaeus, there are no tilapias endemic to Asia. However, species originally from Africa have been widely introduced and have become economically important as food fish in many countries. China, the Philippines, Taiwan, Indonesia and Thailand are the leading suppliers and these countries altogether produced about 1,100 thousand metric tonnes of fish in 2001, constituting about 76% of the total aquaculture production of tilapia [10] worldwide.

In Taiwan, tilapia is also known as the "South Pacific crucian carp," and since its introduction, has spread to aquatic environments all over the island. Introduced in 1946, tilapia have made a considerable economic contribution, not only providing the Taiwanese people with food, but also allowing the island's fish farmers to break into key markets such as Japan and the United States. Indeed, tilapia has become an important farmed fish in Taiwan for both export and domestic consumption. [11] The Chinese name for the fish in Taiwan is "Wu-Kuo" (吳郭) and was created from the surnames of Wu Chen-hui (吳振輝) and Kuo Chi-chang (郭啟彰), who introduced the fish into Taiwan from Singapore. The Taiwan tilapia is a hybrid of Oreochromis mossambicus and Oreochromis niloticus niloticus.

In the Philippines, tilapia has many culinary purposes, including fried, sinigang (a sour soup which sometimes has tamarind, guava, calamansi or other natural ingredients to flavour it), paksiw (similar to sinigang only it consists of vinegar, garlic, pepper and ginger) and many more recipes.

Taxomic Positions of Tilapia

Most tilapia species of the tribe Tilapiani now being used in aquaculture were grouped initially into one genus, Tilapia. The species within this genus were later classified according to differences in their mode of reproduction (Low McConnel; 1959 Trewawas, 1973, 1978, 1982). Species which evolved as substrate spawner but guard their eggs were retained in the genus tilapia while those which orally rear their clutches were grouped into a new species Sarotherodon. Classification of the three genera Tilapia, Sarotherodon and Oreochromis was based largely on the differences on their reproduction and feeding habits.

Classification of Tilapia Species used in Aquaculture

Genus Tilapia (Substrate spawners)
Both parents guard, protect, aerate the breed, and help move clutch to different nest sites. Fry at first feeding are 4-5 mm and show feeble swimming ability. Fry survival relatively low.

Genus Sarotherodon (Paternal/biparental)
Both parents stay close to each other. Eggs and fry brooded in oral cavity up until they are ready for release. Brood may not be collected once released. Fry are between 7-9 mm at first breeding, well developed fins for swimming. Fry survival high.

Genus Oreochromis (Maternal)
Female solely involve in brood care. After spawning, female leaves nest to rear her clutch in safety. Fry brooded up until free swimming. There is an extended period of care during which fry seek shelter in buccal cavity for safety. First feeders have well-developed fins for swimming. Fry survival high.

Sex Identification

Sex identification of tilapia is relatively simple. The male has two openings just in front of the anal fin. The large opening is the anus and the smaller opening at the tip is the urogenital pore. The female has three openings: the anus, the genital pore, and the urinary pore. The genital papilla is usually smaller in the female. Tilapia can be sexed when it has attained the weight of 15 grams. Application of ink or dark dyes to the papillae may increase the accuracy of sexing and may allow sexing of smaller fish. By rubbing ink along the papillae of the tilapia, sexes can be readily distinguished.



Spawning

The Nile tilapia is a mouth-brooder. The male establishes a territory and builds a round nest in the pond bottom. (Usually the diameter of a nest is 30 to 60 centimeters. The size of the nest is correlated to the size of the male). The female enters the nest and lays the eggs. The eggs are fertilized by the male. The female then collects and incubates the eggs in her mouth. The eggs are yellow in color. Eggs hatch in about five to seven days. After hatching the fry remain in the mouth of the female for another four to seven days. The fry begin to swim freely in schools, but may return to the mouth of the mother when threatened. Females do not feed during incubation or the brooding period.

Females spawn every four to six weeks, but may spawn sooner if the eggs are removed. The number of eggs per spawning is related to the size of the female. A female of about 100 grams may produce approximately 100 eggs per spawning while a female of about 100 to 600 grams can produce approximately 1,000 to 1,500 or more eggs per spawning.


TILAPIA HATCHERY MANAGEMENT & FINGERLING PRODUCTION

To meet the demand for tilapia fingerlings, more private hatcheries should be established. Although some fish-farmers specialize in fingerling production, many of them are engaged in fingerling and food fish production simultaneously. As the indury expands, farmers realize the importance of using good quality fingerlings. As long as the demand for fingerlings exists, a well-managed hatchery is a lucrative business.

Brood Stock Selection

Genetic improvement of tilapia is imperative to the development of the industry. Select quality brood stock to improve tilapia production. Choose pure quality stocks and do not allow them to crossbreed with other species to preserve their genetic quality. Tilapia farmers should buy their stocks only from reliable and established sources.

Maintenance of Good Quality Stock

It is necessary to maintain high quality pure stock with the following measures:

1. Prevent the introduction of inferior tilapia species into the brood ponds. Filter all incoming water or use ground water, if possible
2. Use brood fish of about 100 g or more. If larger brood stock are used the original stock can be easily identified after each production cycle. Use the same stock repeatedly, depending on their performance.
3. Adopt an independent culling-selection process for undesirable stock. Always eliminate fish that has questionable characteristics
4. Examine breeders carefully when re-stocking after each cycle.
5. Avoid introduction of breeders from non-accredited sources.
6. Teach laborers and caretakers the importance of preventing genetic contamination.
7. Drain ponds completely and remove all stocks pond reconditioning.


Hatchery Methods

Pond Method

The open pond is the simplest and most common method of fingerling production. In this method, a pond serves both for spawning and rearing. Stock breeders into the ponds and allow to spawn naturally at controlled conditions.

Brood fish stocking rate. Stock pond at the rate at 100 to 200 kg brood stock per hectare at a sex ratio of 1:3 or 1:4 male to female. Brood only fish weighing about 50-100 g. A female brood fish of 90-300 g produces as much as 500 eggs per spawning. However, brood fish may be used continuously for a period of 3-5 years. Use larger breeders to identify them as brood stock.

Collecting, grading and conditioning fingerlings. Collect fingerlings 30-45 days after stocking of breeders using knot 32 mesh seine. Do this 3-4 times per harvest period at an interval of two to four weeks.
Grade collected fingerlings by using 22k, 17k, 14k and 10k nets. Release breeders back to the pond immediately. Condition collected fingerlings by stocking these in "hapa" or tanks for 3 or more days before disposal. Give the fingerlings supplementary feeds at the rate of 3% body weight. However, stop feeding 24 hours prior to disposal. The ideal stocking rate for 'hapa" is 2-3 kg of fingerlings per cubic meter.
The average number of fingerlings harvested should be at least 100,000 pieces per hectare per month or about 1.2 million per hectare per year. Increasing the frequency of harvesting and minimize predation and cannibalism by the parent fish and other predators of the fingerlings.
Recondition the ponds after 120 days or sooner to increase production.
Restock small fingerlings in earth nurseries to reach the desired size of size 22 at 15-30 days and size 17 at 45 days. Stocking rates between 25 to 30 fingerlings per square meter give optimum results.

Routine hatchery pond fertilization. Aside from the basal fertilization, apply organic fertilizer uniformly such as air-dried chicken dung at the rate of 750 kg/ha per week or 3 tons/ha per month.
Apply inorganic fertilizers (16-20-0) at the rate of 100 kg/ha per month. New ponds may require higher rates of fertilizers.
Increase the rate of fertilizer if plankton bloom does not appear within 5-10 days. Apply fertilizer by means of the platform or by the hanging sack method.

Feeding. If manure is not applied, use supplemental feeding feed fish with rice bran at the rate of 2-3% of their body weight per day. Give 1/2 of the daily ration in the morning and the other half in the afternoon. Drain the pond completely after 90-120 days to eliminate predators and prevent inbreeding. To prepare the pond for the next production cycle, refer to "Fishpond Preparation".

Advantages of the Open Pond

* management is very simple, but effective
* the pond serves as spawning and rearing pond, thus, the fingerlings produced are larger compared to those produced through the other methods
No supplemental feeding is required at high manuring rates

Disadvantages of the Open Pond

* the number of fingerlings produced per square meter is lesser compared with the other methods
* the fingerlings produced are not of the same size; they need to be graded upon harvesting.

"Hapa" Method

A "hapa" (net enclosure or "bitinan") is like an inverted mosquito net which the four top corners are tied to bamboo stakes. It is made of fine meshed polyethelene netting. The seams are sewn with nylon thread and double stitched to prevent splitting.
A "hapa", measuring 3 m long , 3 m wide and 1.5 m deep is the most common size used. Usualy, it is installed in ponds, lakes or along river banks with slow moving current. The open part of the "hapa" should be two feet above the water surface.

Advantages of the Open Pond

* production on a per square meter basis is high
* fry are more uniform in size
* fry and breeders are easily handled

Disadvantages of the Open Pond

* management is more complicated and intense compared with the other methods
* brood fish in "hapa" are easy targets of poachers
* "Hapas" may be destroyed or blown away during typhoon or stormy weather
* feeding of breeders and fry is a must

Stocking. In the "hapa" method, the sex ratio of male to female is 1:5 to 1:7. Stock 4-5 breeders weighing 50 to 200 g pe sq m.

Feeding. Feeding is a must in the "hapa" daily for the presence of schooling fry. Two weeks stocking of breeders, scoop out fry and transfer these to tanks, other "hapas" or rearing pond. Feed collected fry a diet in powdered form at the rate of 5 percent of the total body weight.

Collecting fry. Check the "hapa" daily for the presence of schooling fry. Two weeks after stocking of breeders, scoop out fry and transfer these to tanks, other "hapas" or rearing ponds. Feed collected fry a diet in powdered form at the rate of 5 percent of their body weight per day. Feed four times a day until they reach the desired size.

----------

Modern Way of Producing Tilapia Fingerlings

I. Preparing the Fishpond

* Construct a small fishpond in areas having suitable clay soil and abundant water supply, about 10 meters wide, 20 meters long and 1 meter depth.

* Irrigate up to 3 to 5 centimeters (cm.) water level.

* Apply 1 kilo of dried chicken manure fertilizer per square meter (sqm.) of the pond

* Let natural fish food organisms grow in 15 to 17 days.

* Irrigate the pond up to 50 cm. level. The pond is now prepared for stocking of the tilapia breeders/adults.

II. Stocking of Tilapia Breeders

* This is done early in the morning or in the afternoon when the weather is cool.

* The ratio is, 1 male is to 3 female. Avoid to pair many male tilapias because it tends to slow down the production of fingerlings because they tend to eat their own fingerlings due to lack of feed. 1-2 tilapias may be dropped per square meter.

III. Management

Feeding System

* Feed the tilapias twice a day by using a duck layer mash or broiler mash, about 3 to 5 percent of the fish body weight. Do not give feeds with high protein as it tends to make the fish fat and incapable to lay eggs.

IV. Harvesting

The tilapias lay eggs from 20 to 26 days. Three to five days after the eggs are hatched, the fingerlings should be collected early in the morning and transfer it in the rearing net enclosures.

----------

TILAPIA CAGE CULTURE



Introduction

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 Selection

Water 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 Cages

The 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.


----------

Tank Culture of Tilapia


Tank culture of tilapia is a good alternative to pond or cage culture if sufficient water or land is not available and the economics are favorable. Tilapia grow well at high densities in the confinement of tanks when good water quality is maintained. This is accomplished by aeration and frequent or continuous water exchange to renew dissolved oxygen (DO) supplies and remove wastes. Culture systems that discard water after use are called flowthrough systems while those that filter and recycle water are referred to as recirculating systems.

Intensive tank culture offers several advantages over pond culture. High fish density in tanks disrupts breeding behavior and allows male and female tilapia to be grown together to marketable size. In ponds, mixedsex populations breed so much that parents and offspring compete for food and become stunted. Tanks allow the fish culturist to easily manage stocks and to exert a relatively high degree of environmental control over parameters (e.g., water temperature, DO, pH, waste) that can be adjusted for maximum production. With tanks, feeding and harvesting operations require much less time and labor compared to ponds. Small tank volumes make it practical and economical to treat diseases with therapeutic chemicals dissolved in the culture water. Intensive tank culture can produce very high yields on small arcels of land. [continue reading here] (Warning: PDF Document)


L-2409
SRAC Publication No. 282
Southern Regional AquacultureCenter
September, 1989 **

----------

TILAPIA SEX REVERSAL

Male tilapia fish grow faster and much bigger than the females. The males normally weigh frorn 600-800 gms in four months and can even grow bigger, but the females reach only as much as 150 gms within the same period. Because the female tilapia reproduces fast, the over population in the pond retards their growth and causes the death of many.

If the males and females would be put together, it is not easy for harvest time because their growth or sizes would be varied.

Materials:

1. Seven (7) inverted (mosquito) nets,
2. Formula SRT-95 (hormone).

Method:
1. Place in the inverted nets (in the pond) the newly hatched fingerlings from the mouth of the mother tilapia.
2. Feed them with the formula.
3. Do this in 21 days. A kilo of hormone can feed 6,000 fingerlings.

The percentage of reversal when fed with this hormone is 95-99%. When 10 days are past, the fish will not change sex even when they are fed with the hormones. This was discovered by Dr. Rafael Guerrero of the Central Luzon State University in 1977, based on his doctoral thesis at the Auburn University. He did not keep the information selfishly but shared it with the people that now benefit from it. For this, he was awarded the TOYM award and the S&T IBM Award in 1987.
PCARRD Farmnews Vol X11I Sept 1987



SOURCE: da.gov.ph; dost;

Tags:
Agri-Poultry Business