The Assessment of the Health Condition of Salmonids by Non-Specifec Haemolytic (SH₅₀) Activity of Serum

Abstract

Normal salmonid sera were assayed for spontaneous haemolytic activity, SH₅₀ activity, against washed goldfish red blood cells. When juvenile coho salmon Oncorhynchus kisutch and masu satmon O. masou were starved for 10 to 20 days and injected with Aeromonas salmonicida and Vibrio anguillarum intraperitoneally, a correlation between the decrease in the SH₅₀ activity and the increase in severity of starvation and diseases was evidently represented. A similar correlation was followed by naturally diseased salmonids. The SH₅₀ activity reflected the alteration in the state of health. Also, a consideable difference in the SH₅₀ activity was shown by parr-smolt transformation of masu salmon. A possibility of the SH₅₀ activity as a parameter of fish health assesment is discussed.