Change of Rheoreaction in Juvenile Rainbow Trout Oncorhynchus mykiss during the First Days After Surfagon Injection

The short-term (up to ten days following injection) effect of a surfagon injection on rheoreaction in rainbow trout Parasalmo mykiss (= Oncorhynchus mykiss ) at the age of three months was investigated. It was revealed that by the seventh day following injection the fish exhibited no response to manipulative stress. The response to surfagon injection was manifested after ten days; at that point the fish were injected moved mainly downstream.