Isolation of fungi
The samples were washed 2 times before culture on the Gy plus antibiotic medium (1% glucose, 0.25% yeast extract and 50 ug/ml of ampicillin and streptomycin). The cultured medium were incubated at 25 ºC for 2 days and purified by cutting the marginal colony to put on the new medium.
Identification of fungi
The pure culture of fungi were studied to the morphology of asexual zoospore reproduction in sterilized tap water. The genus of isolated fungi were identified by the method belong to Willoughby (1985)
Number of bacteria and fungi from rearing water and stock water
Water samples were collected from egg hatching water, fry rearing water and stock water (holding in 500 ton cement tanks obtained from Phayao reservior). Water samples (10 ml/pond) were taken from approximately 5 cm below the water surface in sterile glass bottles. A tenth ml of each sample were spreaded on NA agar and incubated at 30 oC for a day. The number of colony were counted and calculated for the total number of bacteria as cfu/ml. Another 0.1 ml of each sample were spreaded on Gy plus antibiotic medium and incubated at 25 oC for 2 days. The number of fungi colony were reported as unit of zoospores per ml.
Water qualities in Mekong giant catfish hatchery
Water analysis consisting of dissolved oxygen (mg/l), pH, temperature (Co), alkalinity (ppm as CaCO3), hardness (ppm as CaCO3), total ammonia nitrogen (ppm) and nitrite nitrogen (ppm) from water using for Mekong giant catfish egg hatching, fry nursing and stock water were conducted.