Aquaculture Asia, April/June 1997, 2 (2): 29
Catfish farming is a big industry in Southeast Asian coun tries. Catfish is a species in many ways well suited for aquac ulture. However, there are still some constraints during the nurs ing of the newly hatched fry. For the first 2-3 weeks after hatching, the catfish will not normally accept dry pelleted feed.
During this period the fry are normally fed live feed in the form of Moina and Artemia. The production of Moina is relatively cheap, but time consuming and, not always reliable, especially during the rainy season. Artemia eggs are readily available, but they can cost a bit and are often of varying quality. For the past two years the Danish government has been supporting an Aquaculture Development Programme at Ra nong College of Agriculture and Technology, Thailand. One of the main objectives of this DANIDA-funded project is to im prove local fish production. For this purpose, special emphasis has been put on production of catfish, tilapia and carp. On one occasion we had a large batch of catfish fry, but no avail able Moina or Artemia. To provide an alternative food source, we minced hard-boiled chicken eggs in a blender. This "soup" was subsequently diluted and fed evenly to the fry tanks. The results showed that survival and growth rates were better than we had ever achieved. It should be noted that we used the whole egg, both egg yolk and egg white. The same technique was used for subsequent catfish batches, again with very positive results. This has led us to abandon the use of live feed for rearing catfish.
The procedure used was as follows: For approximately 50,000 newly hatched catfish fry we fed 2 minced hard-boiled eggs 5 times per day, a total of 10 eggs per day. Two eggs and 1/2 liter of water were minced in a kitchen blender for 30 seconds at maximum speed. This
"soup" was subsequently diluted and poured evenly into the fry tanks. The water exchange was stopped for 1 hour after each
feeding. When the water was turned on again, the water ex change time in the tanks was approximately 2 hours. An air stone in each tank gives continuous aeration.
By using the above technique, we normally achieve catfish survival rates of 70-80%. A glass beaker can be a good ex amination instrument. Observe some catfish fry 1/2 hour after feeding. If they have been eating properly, it is easy to see the enlarged white bellies of the fry. If the bellies are not enlarged and white, find out why. Maybe the mincing of the eggs is not thorough enough, so the egg white particles are too big for the fry to swallow.
The DANIDA project hopes that this simple technique can be of use to fish farmers. The same procedure might be ap plied for carp and other Cyprinoid species. (Submitted by Poul Petersen, Technical Adviser in Aquaculture, DANIDA).
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