Pointers on Growing High-Value Finfishes
There’s a growing interest in growing high-value finfishes like seabass, pompano, mangrove snapper and lapu-lapu or grouper. These can be grown in seacages or in ponds. And the good news is that fingerlings are now available not from the wild but from the hatchery. Therefore, the fingerlings are available throughout the year.
Fingerlings can now be sourced from Finfish Hatcheries, Inc., a member of the Alcantara Group of Companies, based in Alabel, Sarangani province. The company also provides useful pointers in growing these high-priced species.
MANGROVE SNAPPER
The mangrove snapper is one of the promising high-value finfish species for culturing in seacages, such as those in the mariculture parks being developed by the Bureau of Fisheries and Aquatic Resources (BFAR) in different parts of the country.
Nursery. For nursery operation, 700 pieces of one-inch fingerlings are recommended for stocking in a cage measuring 4 meters by 6 meters and 1 meter deep. That means 29 pieces per cubic meter. These will grow to 4-inch fingerlings in 25 to 30 days. Double net is used in the cage with a mesh of 0.5 cm and outer net mesh is #17.
Feeding is done at least three times a day, initially at 8 to 10 percent of body weight. For the first 10 days, feed is finely chopped shrimp or fish. From the l1th to 30th day, trash fish is fed.
Grow-out. For grow-out operation, cage with the same dimensions as above may be used. A total of 150 four-inch fingerlings are stocked. These are cultured for 6 to 7 months with a target harvest size of 750 to 800 grams each. The cage is double net with #17 net mesh.
The fish are fed with chopped trash fish based on demand up to satiation, or initially at 6 to 8 percent of average body weight and adjusted based on consumption and response.
The net should be changed at least three times during the whole culture period, or depending on the-degree of fouling.
The above recommendation is based on actual practices documented in Roxas City.
SEABASS
Nursery. Stock 700 pieces of one-inch fingerlings in a cage measuring 4 meters wide, 6 meters long and one meter deep. The fingerlings will grow to 4 inches after a culture period of 25 to 30 days. _ Feeding is done at least three times a day, initially at 8 to 10 percent of average body weight, and adjusted based on the feeding response of the fish. From Day 1 to Day 10, feed is finely chopped shrimp or fish. Trash fish is then fed to the fingerlings from Day 11 to Day 30.
Inside net mesh is 0.5 cm while the outer net is #17.
Grow-out Operations. Cage size is 4 meters by 6 meters and 1 meter deep. Cage is double net with mesh size #17. Stock 150 pieces of 4-inch fingerlings from the nursery. Target harvest size is 750 to 800 grams after a culture period of 6 to 7 months.
Feed with chopped trash fish, based on demand up to satiation or initially at 8 to 10 percent of average body weight and adjusted based on consumption and response. Commercial feed may also be used for feeding.
The net should be changed at least three times during the whole culture period, or depending on the degree of fouling.
The above pointers are based on actual practices documented in Roxas City.
POMPANO
This species is usually grown .in three stages. First is the nursery stage from fry to fingerlings of 1.5 inches in ponds. The second is transition stage from 1.5 inches to 80 grams in brackish water ponds and marine cages. Third is the grow-out stage from 80 to 700 grams in marine sea cages.
Formulated feeds are available at all stages. Health concerns on parasites and algae fouling up the gills are only seen in pond grow-out culture. Marine cage culture is the best for pompano. Pompano school moves a lot. It is best not to disturb them at all.
Grow-out culture can be improved with the use of better quality feeds and growing conditions at sea. Better growth and feed conversion can be attained when the fish grown together are uniform in size. Feed the growing pompano five to six times daily. Don’t disturb the fish at any time. Partial harvesting is not recommended. During the finisher stage give them feed up to 80 to 90 percent satiation, two to three times daily. Do monthly sampling for growth and health monitoring.
GREEN GROUPER (LAPU-LAPU)
There are several species of grouper. The culture for all the species vary very little except for the type of feeds. They are all carnivores and will respond to the same type of algal assemblage.
The marine species grow best in stable water conditions. All effort must be directed to stimulating feed demand and stabilizing algae assemblages. Should the pond water be too green for carnivores, bangus may be introduced into the pond to take care of the algae.
Feeds can be monitored in various ways. Allow for 30 to 45 minutes as consumption time for commercial feeds. Use 6 to 10 percent feed rate when using trash fish. Check consumption after one hour.
Feeding systems vary from species to species. For powder feeds, the “bola-bola” dough method is useful. The grouper feeds may be prepared with trash fish as marshmallows made by using fish cutters, mixers and extruders. The dry matter consumption will have to follow the feed guide.
Floater feeds can be delivered by automatic feeders. It is necessary to invert the metal plate to direct the feeds to a 3-meter by 3-meter feeding area enclosed by a 60cm cloth or net mounted on bamboo posts 30 cm above the water and 30 cm below the water surface to minimize floater feed drift off.
Depending on density and biomass, one paddle wheel may be turned on all the time. There should be a nighttime aeration capacity of lhp per 1,000 kilos of biomass.
If the culture is done in cages inside the pond, arrange paddle wheels so that the cages will have sufficient aeration with the water current generated by paddle wheels.
Be vigilant to watch for the first signs of fish discomfort. Diseases can set in when conditions of stress happen. Always monitor for transparency, weather, and water quality. When you get reddish brown to red water, stop feeding and correct the situation. The first sign of a problem is poor fish appetite. Do the troubleshooting immediately.