Apr 18, 2009

Catfish (Pangasius) Culture


Catfish of the type Pangasius spp is commonly called as river or silver stripped catfish, Siamese shark, sutchi catfish, or swai catfish. This catfish species live in freshwater and endemic to the Mekong basin. It is a riverine catfish belonging to the members of the family Pangasidae. It exhibits fast growth when cultured given a good environment.

It is cultured due to its strong market demand, fast grower, few countries dominate the culture production, and being the 3rd most important freshwater fish group within aquaculture sector. Pangasius is now cultured in several countries in the world like Thailand, Nepal, Pakistan, India, Bangladesh, Vietnam, Laos, Maynmar, Indonesia, and Cambodia.

Pangasius is an air-breathing catfish that can tolerate low Dissolve Oxygen (DO) of the water. It can be cultured in fishponds, concrete tanks, fish cages or fish pens.

Common Cultured Pangasius:

• Scientific name: Pangasius hypophthalm. English name: Sutchi river catfish.
• Scientific name: Pangasius bocourti. English name: Bocourts catfish

Site Selection

1. Efficient source of water
2. Free from pollution
3. Free from any disturbance
4. Free from poachers
5. Source of electricity

Size of Culture System

Pond
1. The ideal pond compartment is 1,600 to 2,400 sqm.
2. The ideal water depth is 1.5-2 meters.

Cage
1. The ideal size is 10×10 meters.
2. The ideal depth is 5 meters.
3. Stocking density is 15-50/m3

Pond Preparation - Pond preparation is the same as general preparation for fish ponds.

1. Draining and sun drying. Sundry the pond until the pond bottom cracks to eliminatedepending on the culture environment. Stocking should be done early morning or late afternoon. Survival rate of Pangasius spp. is estimated to be 80-90%.unwanted fish species and condition the pond.
2. Repairing of dikes and gates. Dikes and gates should be repaired to avoid entry of other fish and escape of stocks.
3. Eliminating predators. Predatory fish species should be eliminated to promote better yield and harvest.
4. Liming. Liming is done primarily to condition pond soil, since Pangasius
spp. can tolerate pH ranging from Q.5-7.5.
5. Filling of water. Fill the pond with water to about 1.5m to 2m deep, to provide a wide environment for the stocks.
6. Stocking/stocking density. Pangasius spp. can be stocked at a rate of 3-15 pcs/m2

Pond Management

1. Feeding/feeding management. Pangasius can be fed with kitchen waste, rice bran or pelleted feeds (recommended for faster growth and better fish quality) at a rate of 2.5% of their average body weight (ABW) and will be adjusted bi-weekly. Feed Conversion Ratio (FCR) averages to 1.5:1, which makes it a suitable for culture. Pangasius is omnivorous (eat oth plants and animals) during their first year and become herbivorous for the following years.

Since they are omnivorous, the Pangasius Catfish or Iridescent Shark Catfish will generally eat all kinds of live, fresh, and flake foods. To keep a good balance give them a high quality flake food or pellet everyday. Feed brine shrimp (either live or frozen) or blood worms. As they get older they loose their teeth, and like the Pacus, become more and more vegetarian.

“Home-made” mixture of boiled vegetables, rice-bran and broken rice may also be used for feeding.

2. Water management. Water is important for all fish, so optimum conditions for certain parameters of water should be the primary factor to consider in engaging to fish culture. Water quality parameters like pH (6.5-7.5), Dissolve Oxygen (DO) (0.1 mg/l), Temperature (25-30° C), Salinity (<2 style="font-weight: bold; font-style: italic;">3. Sampling. Sampling is done to monitor the growth of stocks and to compute feeds to be given to the stocks for the following days. This is also done to see if the stock reaches its marketable/harvestable size. Since Pangasius spp. is fast grower fish, sampling is mandatory.

Harvesting

Harvesting can be done in partial (selective harvesting) or total harvesting. Pangasius spp. can be harvested for about 5-6 months of culture period. lt can reach the weight of 1-1.5 kilogram in 5-6 months culture given the proper pond management.

For more information, contact: Bureau of Fisheries and Aquatic Resources (BFAR) San Fernando, Pampanga Tel: (045) 455-0878, Fax: (045) 455-0823 Email: bfar3@pldtdsl.net, bfar3@yahoo.com

References: www.bar.gov.ph, 1. Culture of Pangasius spp. EntrePinoys Atbp. September 2008. 2. Palma, Adelaida L. Breeding and Culture of Pangasius. DA-BFAR-NIFTC.

Apr 13, 2009

How to Control Aphids in Ampalaya


Aphids, Aphis gossypii Glover, suck the sap of leaves. This results in curling and yellowing of leaves, stunted growth, and even death of the whole plant. More importantly, the aphid is a vector of the cucurbit aphid-borne yellow virus (CABYV) which is similar to the “namamarako” disease in ampalaya.

The virus disease causes curling, thickening, and yellowing of leaves, significantly decreasing in female flowers and consequently fruits.


The virus disease is managed by destroying infested plants to prevent further spread.

Management

* Monitor the plants regularly for the initial infestation of aphids. Remove the leaves or uproot the whole plant if necessary.
* Control the ants that carry aphids to the plants by spraying them with any green-label insecticide.
* Control aphids by spraying water or chilli-soap solution at high pressure that will dislodge the pests from the plant, disrupting their life cycle.
* If insecticide is resorted to, use methomyl or carbaryl. Do not use pyrethroids that are purely contact insecticides with no fumigating effects, hence cannot reach the aphids underneath the leaves. Read the label and follow strictly the instructions to avoid contamination.
* The growth of sooty molds is an indirect damage due to the honeydew secreted by the aphids. Such growth hampers photosynthesis that finally kills the plant.

Source: PhilRice and JICA, 2007. Training Guide for Vegetable Production in the Philippines. Maligaya, Science City of Muñoz, Nueva Ecija. Prepared by staff members of PhilRice Batac, Ilocos Norte