Practical use of hemochemical assessment in cultured yellowtail [Seriola quinqueradiata]

The hemochemical assessment was made on the yellowtail Seriola quinqueradiata in July and September, 1983. The specimens examined were one year old fishes weighing about 2, 300g. They were fed on frozen sardine (groups I and II) or thawed sardine (group III), and reared in seawater of temperature about 28°C. In order to minimize the stress effects of handling, fish were angled, and then blood samples were collected by cardiac puncture with heparinized syringe within three minutes. Using these samples, various plasma constituent levels or enzyme activities were determined. In group I, some Pathological changes were observed in intestine (reddening), peritoneum (adhesion) and opercle inside (reddening) possibly resulted from feed trouble. Various blood constituent levels or enzyme activities remained within the normal limits, suggesting that feed trouble was slight. In group II, in which a few dead fish was found every day, pathological changes were similar to those in group I, but the symptoms were more serious than in group I. Alkaline Phosphatase (EC 3.1.3.1.) activity and inorganic phosphorus level were lower, whereas chloride level was higher than those of group I. Reduced bony growth and feed trouble were seen. In group III, that was in worse condition, pathological changes were observed in various organs, and were parasitized by Benedenia and/or Caligus. Levels or activities of hematocrit, hemoglobin, urea-N, total cholesterol, aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.1), and alkaline phosphatase were lower than those of group I, whereas chloride level was higher. These results suggest that this group suffered from malmutrition, hepatic malfunction and low metabolic rate.