CULTURE OF Pseudodiaptomus malayalus IN LABORATORY CONDITIONS PROVIDING THREE DIFFERENT ALGAL DIETS

Copepods form an integral part of the diet for newly hatched larvae of fishes and other higher aquatic organisms. When it comes to staple diet for the larvae the highly pronounced name is that of the copepods and in copepods it is the size which forms the major reason apart from its nutritional attributes. The present work was conducted on such a species of copepod Pseudodiaptomus malayalus, collected from the Cochin backwaters. When it comes to larval feeding nutrient enrichment plays a major role. Providing P.malayalus with the best diet that promotes growth and reproduction with surplus nutrients forms a key responsibility of the culture practitioners as it in turn nurtures the fish larvae feeding on it. The present work is programmed in such a way to assess the best diet for the P.malayalus under controlled conditions.

P.malayalus brooders were isolated from the crude samples collected from the Cochin backwaters. Three 500 ml beakers with 250 ml sea water were set for the study. The water was kept for few days to set the water quality to the referral points. A mature brooder was introduced on to each beaker. The P.malayalus was starved for 24 hours before the feeding experiments. Three algal diets such as Isochrysis galbana, Pavalova lutheri and Thalasiocera mala was provided in each culture beakers. The study was conducted for a period of 20 days to cover the complete life cycle of the copepod species.

The studies revealed that the P.malayalus feeding on Pavlova lutheri had high number of young ones. The P.malayalus fed with Isochrysis galbanashowed second highest number of larvae and those fed on Thalasiocera mala had the least number of young ones. To confirm the findings the experiment was repeated in triplicates and the observations were found to be similar. The results are shown in Table. 1.

Hence we could conclude from the study, that the P.malayalus survives its best when fed with Pavlova lutheri followed by Isochrysis galbana.