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Freshwater Prawn Culture

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Growing freshwater prawn is a promising alternative to the expensive  lobster and tiger prawn. The freshwater prawn, locally known as ulang,  can be substituted for lobster and tiger prawn (sugpo) because of their  appearance and excellent taste. Among the 15 species of freshwater prawn in the  Philippines, the most popular to culture is the macrobrachium rosenbergii, also  known as udang in ilocano, kising-kising in Pangasinan, and swahe in other  regions.

Grow out Farming of the Giant Freshwater Prawn aquabusiness The  macrobrachium rosenbergii is appealing to culture because of its rapid growth  performance and ability to survive and grow in turbid water conditions. Ulang  can tolerate moderate temperature and salinity changes, and can be caught in  tributaries and cultured in ponds, tanks, cages, and rice paddies. They feed on  anything such as terrestrial animal feeds, fish feeds, kitchen leftovers, and  vegetables like carrots, winged beans, etc.

Freshwater prawn can be used in polyculture together with tilapia and carp.  They can tolerate temperature up to 34oC and actively feed at night.  They consumed less feed than tilapia since they are nibblers and slow feeder.  They grow to a maximum size of more than 1 kilogram per piece and they command  high price in the market.

Grow-Out Operation of Ulang

Factors affecting success of grow-out operation:

1. Feasibility of the site

2. Water Supply/Water Quality

3.  Topography

4. Quality of soil

5. Free from flooding

6. Quality of  Stock

7. Market acceptance

8. High level Management practices

9.  Peace and order situation

I. Procedures in Pond Operation:

Pond Preparation

1. Pond draining – To collect eliminate old stocks,  predators and unwanted species.

2. Pond poisoning – Application of biodegradable organic materials such as tea seed cake and tobacco  dust to kill all unwanted species.

3. Pond washing – to  remove the effect of toxic chemicals when insecticides were used.

4. Leveling of pond bottom – removes excess mud and dirt, ensure complete drainage and facilitate ease of  seining during harvesting.

5. Sun drying – helps eliminate  and evaporates toxic gases & ammonia especially in old ponds

6. Screening of water inlet and outlet – prevent entrance of  unwanted species and escape of stocks

7. Filling the pond with  water –Fill the pond with water from 0.8 to 1.5 meters depth.

8. Application of lime– The rate of application is 100g / m2 or  1,000 kg/ hectare.

9. Basal fertilization

 Grow out Farming of the Giant Freshwater Prawn aquabusiness

10. Installation of Artificial shelters – arrange the shelters  in the pond (30 – 50 pcs/1000m2).

II. Nursing of Post Larvae (PL) to Juvenile

Nursing of PL to Juvenile Prawn– The size of the Post larvae  ranging from 1.5 to 2.0 cm must be reared to juvenile size of 5 cm to 8 cm  before transferring them into the grow-out ponds to attain marketable size.

a. Nursery Ponds. The size of the pond must be 50 sq.m. with  a depth; 0.8-1.5 m

b. Artificial shelters. This are placed in the nursery ponds  to serve as hiding place of the Post larvae during molting. Artificial shelter  is needed because when prawns are soft shelled they will be eaten or  cannibalized by the hard shells prawn. The following can be used as artificial  shelters:

  • twigs, bamboos , sampaloc twigs
  • pipes, PVC, or recycled materials  like nets
  • bricks or stones
  • used mineral water bottles (250-300  ml)

c. Nets used for substrate can be suspended from float across the pond  and weighted with sinkers to serve as hiding place for molting prawns to prevent  or reduce cannibalism.

III. Growing of Juvenile to Marketable Size

Stocking Density

Extensive – The stocking density is 1-3 pcs/m2, with the use  of fertilization only (chicken manure and 16-20-0) at a rate of 1,000-2,000  kg/ha and 100-200 kg/ha respectively for basal application.

Semi- intensive – A stocking density of 4-8 pcs/m2 with the  use of fertilization and feeding. A monthly exchange of 30% of water in the pond  is done to maintain water quality

Intensive – The stocking density of 10 pcs /m2 and above  with feeding, fertilization, frequent water exchange and aeration using paddle  wheel is also done to ensure enough supply of dissolve oxygen for the prawn.

Stocking Procedure

Acclimatize the prawn juveniles into the pond water for 10-15 min. before  releasing the prawn in the pond water to prevent thermal stress that will cause  mortality.

CAUSES OF MORTALITY:

a. Cannibalism- due to lack of food and shelters b. Predators – mudfish,  catfish, frogs c. Water pollution – insecticide, pesticide, industrial waste  products

Types of Feeds for Commercial Farming of Ulang

1. Live or fresh food (termites, earthworm, insects 2. Plant vegetable  feedstuffs 3. Formulated diets 4. Reformulated diets (ground tilapia  feeds mixed with fish meal & starch as binder) 5. Chicken pellets (to be  given during the first 2 mos. of culture) 6. Ground fish flesh mixed with  cooked broken rice (to be given after two mos. of stocking) 7. Tilapia  sinking pellets 8. Trash fish

Initial feeding rate using trash fish: • 5% of total body weight

For dried diet, chicken pellets/fish feed: • 3% of total body weight • prawn are nocturnal feeder 40 % of feed ration must be given at night.

Regular water quality monitoring and  feeding activities of the prawn must be properly observed.

DETERMINATION OF AVERAGE BODY WEIGHT (ABW), DAILY FEED RATION (DFR),  TOTAL FEED REQUIREMENTS (TFR) FEED CONVERSION RATIO (FCR)

Grow out Farming of the Giant Freshwater Prawn aquabusiness * The  closer the FCR to 1.0 kg. The better is the feeds. Good feed have FCR’s of  between 1.5 to 2.0 kgs.

Harvesting of Ulang

Harvesting of ulang can be done when they reached its marketable size. After  4to 5 months of stocking, ulang can be harvested through selective harvesting or  total harvesting.

Methods of harvesting

1. Selective – this is done by seining the prawns using size  17 net. The bottom of the seine net should be kept intact on the pond bottom to  avoid escape of the prawn.

2. Total harvesting – this is done by total draining of the  pond. The prawns can be collected in the catch basin manually by using scoop net  or with bare hands.

Marketable Sizes of Prawn After 4 To 5 Months Culture Grow out Farming of the Giant Freshwater Prawn aquabusiness

Measurement of length is from tip of the rostrum to end of the telson

Simple Cost Estimate (1,000 sqm Ulang Fishpond  Project) Grow out Farming of the Giant Freshwater Prawn aquabusiness

For more information please write to:

The Project Manager BFAR-NFFTC CLSU, Muñoz, Nueva Ecija, Philippines

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Author: qdfriends

QDfriends bonded together for the purpose of helping others, and respecting themselves, their culture and the environment.

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