Liquid culture of Panagrolaimus sp for use as food for marine aquaculture shrimp and fish species

Free-living nematodes have potential to be used as live food for early life stages of several species in marine aquaculture. Panagrolaimus sp. displays several favourable characteristics for this application. The present study proved the feasibility of propagation in monoxenic liquid culture on Saccharomyces cerevisiae. The development of yeast cell density, nematode numbers and size distribution was assessed daily for 15 days. After a lag phase of 4 days the inoculated first-stage juveniles started development to adults. Yields in terms of nematode number as well as biomass were highly variable. The maximum number of nematodes varied from 45 000 to 238 000 ml(-1) and maximum biomass from 49 to 143 g l(-1). Information on size, dry and wet weight of the nematodes is provided. The size spectrum of Panagrolaimus sp. individuals ranged from 176 x 8 mu m to 1377 x 61 mu m and 8.15 to 3202.39 ng wet weight. Water content of the nematodes was 71.7 +/- 2.5%, so dry weight per individual was 2.31-905.95 ng. Differentiation of juvenile stages by body length was not possible. Based on comparison of dry weight per individual the Panagrolaimus sp. might be used as a substitute for rotifers, a commonly used live food organism.