Previous Page Table of Contents Next Page


3.1 Polyculture

3.1.1 Bangus and Shrimp Penaeus spp. and Metapenaeus sp.

Shrimp culture in bangus pond is a method used by some managers to increase income. Bangus are the primary crop in polyculture unless they are stocked to control algal growth in ponds primarily used for shrimp culture. Managers who are not familiar with shrimp culture should start on a small scale to minimize possible losses. Shrimp seedlings are generally more expensive than bangus, and shrimp seedling sources are not as dependable.

A brief evaluation of shrimp species suitability for pond culture follows:

3.1.2 Sugpo (Penaeus monodon)

  1. attain a large size and bring a good price

  2. can grow in salinity up to 40 ppt

  3. optimum salinity thought to be 5 to 25 ppt

  4. competition among managers for existing supply of seedlings induces high prices

  5. difficult to harvest because they tend to swim against the current

  6. survival is often low.

3.1.3 Penaeus merguiensis and P. indicus

  1. grow rapidly for two months after stocking, and will reach an average weight of 8 grams in that period

  2. seedlings are abundant

  3. survival is high in pond culture

  4. cannot tolerate salinities below 5 ppt or above 40 ppt

  5. seedlings taken from wild stocks are difficult to identify

  6. cannibalism is a problem

  7. seedlings are subject to handling damage

  8. mortality is a problem if P. merguiensis and P. indicus are held in ponds more than three months.

3.1.4 Penaeus semisulcatus

  1. survives well in pond culture and brings a relatively high price, but grows slowly

  2. does best in high salinity

3.1.5 Metapenaeus ensis

  1. is tolerant of low salinity and high temperature pond survival is high

  2. seedlings are abundant in the wild

  3. sexual size disparity is small

  4. mature size is small compared to other shrimps, and therefore the price is lower.

A properly engineered pond with adequate water and good drainage should be used for shrimp polyculture. Old ponds should be modified, if necessary, to prevent introduction of predators in the water supply. Clay-loam soil is best because of water retention and food production. The pond site should be accessible for transportation of inputs and production from the ponds. Availability of ice should be considered before starting shrimp culture. Wild caught fry should be available. A means of pond aeration should be on hand.

Shrimp culture requires deeper water than is usually used for bangus production. A minimum of one meter of water should be maintained in the pond and 1.5 m is better. Gates should be constructed to prevent introduction of predators. An interior peripheral trench five meters wide and 0.75 m deep should be dug for temperature, and molting shelter for the shrimp (Illus. 4).

A shelter of 1 m long twigs inside the peripheral canal will increase survival by providing cover for the shrimps during molting. Shelters also help prevent wind movement of algae. The usual stocking rate is one juvenile “sugpo” per cubic meter of rearing water. Bangus should not be stocked until the “sugpo” seedlings have been in the pond two months.

Water movement, which increases production of “sugpo”, can be effected by outlet and inlet gate management.

Other penaeid shrimps can be stocked and reared using many of the same ideas used in “sugpo” culture.

3.2 Tilapia Culture

Cultivation of tilapia can be undertaken in brackishwater fishponds whenever there is shortage of bangus fry. In the past, tilapia was considered a pest in brackishwater ponds due to its destructive activities, however, technology of population control and management is opening bright prospect for its production. Tilapia prices have risen to the level of “bangus”.

There are three species of tilapia introduced in the country:

  1. Java tilapia (Tilapia mossambica)

  2. Nile tilapia (Tilapia nilotica)

  3. Zill's tilapia (Tilapia zilli)

The Java and Nile tilapia feed on plankton, aquatic vegetation worms and other organic materials while Zill's tilapia is a herbivore.

3.2.1 Breeding

The male of Java and Nile tilapia build nests where the female lay about 500 eggs, while male, releases milt to fertilize the eggs. The male or female carries the eggs in their mouth until hatched, and thereby allows the young to enter her mouth for protection.

The female Zill's tilapia on the other hand spawn on substratum and is not a mouth breeder, and can lay as much as 5,000 eggs. The young are guarded by both parents.

3.2.2 Source of fish seed

Java tilapia is present in most brackishwater fishpond areas in the Philippines while the Nile tilapia is available in some stations of BFAR and other breeding establishments.

Illus. 4

Illus. 4. Model Pond

Tilapia seed can be collected from brackishwater fishponds during harvest of bangus, or a pond may be utilized for breeding.

3.2.3 Population Control

Tilapia is prolific in nature so population control is necessary to obtain large-size fish. There are however, several methods that could be applied and these include mono-sex cultivation and use of predators. Mono-sex cultivation

- Cultivation of either male or female can stop population growth of tilapia in pond. It is advantageous to use male tilapia which can be separated by hand or by induced sex reversal.

  1. separation of males from females can be done on tilapia 10 cm or longer by looking at the urogenital papilla.

  2. induced sex reversal - this is a new technique of obtaining mono-sex tilapia by hormone treatment. Tilapia fry are fed with the synthetic male sex-hormone, methyltestosterone which can change females to functional males. Use of predators

- For population control, the use of predators such as ten pounder “bidbid” by stocking them in a tilapia pond will control the population by eating some of the young tilapia. The ratio of the tilapia to the number of predators has been thoroughly studied.

3.2.4 Cultivation

The procedure in the cultivation of tilapia is almost the same as that of “bangus”. A pond with lab-lab or “lumut” growth can be stocked with fingerlings, at the rate from 1,000 to 5,000 fingerlings per hectare. After the natural food has been consumed, the tilapia can be harvested or if a bigger size fish is desired they can be transferred to other ponds or given supplemental feeding.

3.2.5 Harvesting

Tilapia can be harvested by the following methods:

  1. Seining - tilapia can be confined in a catching pond by draining or driving them with net. Once confined in the pond, the tilapia can be harvested by seining.

  2. Gill net - this is a selective method of catching tilapia.

3.3 Shrimp Culture

Shrimp culture in the country is confined mostly to “sugpo” or P. monodon. Although other species like P. merguiensis (hipong puti), P. semisulcatus (bilik) and Metapenaeus spp. (suahe) are found in ponds with the culture of bangus, “sugpo” is the most popular. Except in few isolated instances shrimp culture is generally a secondary source of income in polyculture.

Substantial progress has been made in developing new culture technique. Some of the problems encountered in the industry have been solved by research. Shrimp culture practices that are observed to be used to advantage by others to improve their culture technique may be adopted.

3.3.1 Considerations and Requirements in Shrimp Culture

Various criteria that are to be followed in “sugpo” pond:

  1. P. monodon grows only after molting and during this time it is vulnerable to predators and cannibalism. It is necessary to get rid of predators by pond management and application of pesticides.

  2. Subjection to stress factors such as high temperature, starvation, low oxygen level in the pond must be minimized or completely avoided.

3.3.2 Pond Lay-out for Progression System of Management

An improved lay-out for the progression method of shrimp culture is a pond system which consists of nursery pond (NP), a transition pond (TP) and rearing pond (RP).

Type of PondSize of PondGrowing Period
Nursery pond12
Transition pond32–3
Rearing pond52–3

Shrimp usually stop growing in ponds after 2 months but start to grow again if put in another pond with a good supply of natural food. Transfering is done when tidal fluctuation is greatest. Lower the pond water level at low tide and allow tidal water into the pond at high tide to get the shrimp moving to the other pond or collecting at the catching pond.

3.3.3 Supply of Seed Stock

  1. Methods of collection of fry

    1. Bundles of twigs are placed and fixed by suspension in shallow areas. Collections are made by placing a scoop net under the bunch of twigs.

    2. By push nets and scissor nets.

    3. Tidal inflow and trapping in pond. The disadvantage in this method is that quantity collected is uncertain.

    4. Try method.

  2. Fry transportation in plastic bags placed in styrofoam containers

    300 fry P 20–24 or 5,000 P 17–18 are transported in each bag. Sufficient oxygen is added to fill the bag. Optimum temperature is 27–30°C to minimize mortality.

3.3.4 Pond Management Pond preparation

  1. Drain the pond completely and allow the pond bottom to dry for a week. While drying undertake the following:

    1. Repair of dike and canal

    2. Cultivation and leveling of pond bottom as necessary

    3. Screening of pond gate by placing bamboo screen with nylon

    4. Place bag net during admission of tidal water.

  2. Liming for acidic ponds - Quicklime (CaO) at 100–500 kg/ha (Follow lime recommendations, sec.

  3. Elimination of pests and predators

    1. Mechanical - unwanted fish species are killed by thorough drying and draining.
    2. Slowly draining the pond to allow concentration of snails to small area where treatment is done to kill them or manual gathering.
    3. Repair of dikes for seepages and crab holes.
    4. Chemical - for snails - Brestan, Aquarian used at the dosage prescribed on the package. Tobacco dust at 200–400 kg/ha can be applied to eradicate fish and snails, or 12–15 kg commercial nicotine product.
    5. 400-100 kg rice bran, flood to 10 cm; leave for 1 week. Fermentation will kill aquatic predators.
  4. After 1–2 days, apply organic fertilizers. Spread chicken manure throughout the pond at 1,000 to 2,000 kg/ha. After 4–5 days, admit water up to 15 cm depth.

  5. Inorganic fertilization - broadcast 2–4 bags/ha of 18–46 or 4–6 bags/ha of 16–20 for lab-lab. For plankton growth, the pond is filled to 60 cm depth and inorganic fertilizer is used following the platform method.

  6. Water change - change water every 12–14 days by draining about ⅓ and freshening it to add food organisms to the pond. Stocking

  1. Stocking time - during sunny days, stocking time should be done preferably in the morning or late afternoon. Stocking can be done any time of the day provided it is cloudy and pond water temperature is low, and the water is not turbid. Stock should be post larvae P10-P20. Stocking density for monoculture is 10,000–20,000 “sugpo” juveniles, per ha, polyculture - 5,000 – 10,000 “sugpo” juveniles per ha. Transfer - from nursery pond to rearing pond

Methods of transfer:

  1. Shrimp trap or “bakikong”

    1. Install as many fish traps as are available along the dike with a lamp to attract the shrimp.

    2. Gradually reduce water depth in the pond before incoming tide.

    3. Admit tidal water.

    4. Catch shrimp juvenile by means of scoop net.

    5. Carry them by pail to the ponds for stocking.

  2. Bag net or “lambat” - bag net operation is done by lowering water level, and allowing the rising tide into the pond.

  3. Catching pond method

    1. Remove flash boards and gate screen from the pond gate.

    2. Reduce pond water level to half depth.

    3. Allow tidal water in the evening to allow stock to enter the catching pond.

    4. Scoop net, seine or manual catching is done.

  4. Manual method

    1. Reduce water to the level of the peripheral canal by draining slowly.

    2. Catch remaining stock in the canal by means of seine net, scissor net, dredge net or pick them up by hand. Rearing shrimp Water management
  1. Nursery pond - Depth of water is 25–30 cm at stocking time and raised 10 cm every spring tide to a maximum of 60 cm.

  2. Rearing pond - Depth of water is 35–40 cm at stocking time gradually raised by 10 cm every spring tide to a maximum of 100 cm. Pond management
  1. Replenish pond water every spring tide.

  2. During stress, due to low oxygen or high water temperature, add tidal water for replenishment.

  3. During heavy rain and presence of low surface water salinity, drain top water by opening the slab of the first layer to allow to drain and replenish the water by opening the slab during high tide, or circulate the pond water by means of a motorized banca.

  4. During neap tide seal the gates and check seepage to retain pond water level.

  5. Dikes' seepages and leakages should be checked daily. Natural food in ponds
  1. Lab-lab - High salinity in growing lab-lab is not compatible to growing condition of P. monodon. Canals are needed for the P. monodon because of the low level of pond water to grow lab-lab.

  2. “Lumut - Support good growth of P. Monodon and other shrimps. Moderate growth is desired because when it becomes excessive the sugpo are entangled and trapped in the net of algae where they die. Supplemental feeding

At the early stages the sugpo feeds mostly on lab-lab, lumut and plankton. As sugpo grows bigger however, they become carnivorous. Feeding may be necessary and sometimes in the morning. Types of feeds used
  1. Fresh trash fish mixed with rice bran.

  2. Mussel meat, shrimp heads, small crustaceans.

  3. Slaughterhouse and poultry leftovers chopped into small pieces scattered in the ponds, usually along the edge of the ponds or shoulder.

  4. Skins of animals not for human use.

  5. Commercial feeds in the form of pellets. Harvesting

  1. Shrimp trap - “Aguila”, “bakikong” and picking by hand.

  2. Catching pond method

  3. Seine net

  4. Cast net

  5. Trap with bait

  6. Bagnet at the pond gate during water discharge at night. Signs of trouble in ponds

  1. Foul odor due to decomposing algal growth.

  2. Swimming in the surface during daylight.

  3. Changes of water color - greenish to grayish brown color.

  4. High temperature above 32°C of pond water.

  5. Gobies swimming in stress on the side of the pond.

  6. Snails climbing out of the water.

  7. Discoloration of shells of the sugpo and sluggish placid condition.

  8. Low oxygen level of pond water.

  9. Low pH. Remedial measures

  1. Change water by draining from the bottom and replenish.

  2. Mix water to oxygenate by motorized banca if tidal water cannot be introduced.

  3. Remove dead fish.

  4. Suspend fertilization.

  5. Add lime 100 ppm for low pH. Other factors to be considered

  1. To minimize growing period risk, rearing time should be reduced through better management.

  2. Constant inspection of the area to look for signs of trouble.

  3. Profit-sharing with workers as an incentive to make them work reliably and effectively.

  4. Proper planning and marketing.

  5. Proper recording of events during the operation for evaluation of the results as a basis for the next cropping period.

3.4 Culture of Crab, “Alimango”, Scylla serrata

The crab Scylla serrata Forskal, locally known as “alimango”, is common in the mangrove swamps throughout the Philippines. It is the biggest and most highly esteemed edible crab in the country and the most expensive, particularly the female when the eggs are well developed. In Camarines Norte, crab is cultured from the time swamplands are converted into fishpond.

3.4.1 Breeding

The “alimango” breeds throughout the year, with a peak season from May to September. Mating pairs can be seen swimming around in the ponds and the female, carrying a big mass of eggs in its abdomen, can usually be caught.

3.4.2 Collection of Seedlings

“Alimango” spawns in the sea and the larvae are carried by the tide to the coast. The juveniles migrate to the coast to stay in tidal flats, marsh lands, and estuarine areas in brackishwaters. In Camarines Norte, crab seed measuring about 2 cm are collected in places like Mercedes, Paracale and Capalonga with traps like the “bubo” (bamboo cage), “bintol” (lift net), “sakag” (scissor net), “baklad” (fish corral) or sometimes caught by hand.

3.4.3 Method of Culture

In the Philippines crabs are incidentally cultured with the milkfish. The seedling of crabs, larvae, or fry enter the pond when sea water is allowed in. Seedling of crabs can also be purchased from fry collectors. In Camarines Norte where seeds are available throughout the year, young “alimango” delivered to fishponds usually have no pinchers as they are generally broken off for easy handling and to prevent their fighting and hurting each other during transport. The pond owners do not keep proper accounts of what they stock and follow a system of repeated stocking and harvesting.

3.4.4 Feeding

The “alimango” is a voracious feeder. It prefers to crawl on the pond searching for food, but also can be seen swimming on the surface. In ponds, they feed on natural food such as algae and crustaceans. Fishpond owners depend on natural food, as they are reluctant to invest in artificial feeds. Some operators practice supplementary feeding with cheap fish, kitchen refuse or leftover foods. If properly fed, crabs can be harvested within 6 months after stocking.

3.4.5 Harvesting

“Alimango” can be harvested with different kinds of traps. Generally, only the big ones are harvested and the smaller ones set free to grow in the ponds.

Previous Page Top of Page Next Page