Carl Emilio Bagarinao, Raynard R. Delos Reyes, Lean Robert A. Gonzaga (March 2005)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
This research aimed to develop and test an alternative hatching system for adhesive catfish eggs. Different densities of eggs were stocked in the new hatching system and the hatching rates were compared by stocking density, and by hatching system. The hatching system was easily assembled with locally available materials. It consisted of plastic bucket as the water tank, a gravel bed as biofilter, a plastic a la McDonald hatching jar, an air pump, and a PVC airlift pump made of a perforated PVC pipe intake formed in a square. The air pump was connected near the base through a rubber tubing to produce the needed flow rate that would move the water through the biofilter to be airlifted into the hatching jar. Water flow rates measured at the outflows of the hatching jars averaged about 985 ml/min, and the turn over rate in the jar was 30x every hour. Three units of the experimental hatching system were tested and worked very well for the incubation and hatching of catfish (Clarias gariepinus) eggs at the Aqua site Hatchery in Barotac Nuevo, Iloilo. Incubation period was 22 hours for each of three spawning runs done between 3 and 24 November 2004.
The experiment on the effect of egg stocking density on hatching rate was done according to a complete randomized block design. Three stocking densities were tested (10, 000 eggs, 20, 000 eggs, and 30, 000 eggs per 2 L hatching jar), with three replicates over time, the replicates using eggs from three females in three induced spawning runs. Hatching rates were similarly high (86-90%) at the three egg stocking densities tested. Although hatching rate was highest at 30, 000 eggs 2/L, there was no significance difference from the lower densities. Hatching rates in the experimental hatching system tended to be higher by 2-16% (average 7.4%), but were not significantly different from those in the Aqua site system. Further studies and improvements should be made on the new hatching system so it can be used in commercial catfish aquaculture.