Clinical studies of fish blood: importance of sample collection and measurement techniques

Effects of blood sample collection and measurement techniques were assessed for blood gas tensions, acid-base status, and hematologic and plasma biochemical values of rainbow trout. Blood samples were collected via intraaortic cannulae from immersed, unrestrained fish and from emersed, restrained fish. The samples were analyzed at either fish body temperature (10 to 14 C) or clinical blood analyzer temperature (37 C); results obtained at 37 C were back-adjusted to fish body temperature, using standard mammalian temperature-correction factors. Fish emersion and handling for 30 seconds significantly (P less than 0.05) altered blood PCO2, acid-base status, and hematologic and plasma biochemical values. The results were consistent with respiratory acidosis and hemoconcentration. The use of mammalian temperature-correction factors for determination of fish blood gas tensions and acid-base status yielded values that were significantly (P less than 0.05) different from those measured directly at fish body temperature.