The assessment of h emoglobin levels (Hb) has become a routine measurement for the evaluation of the health and welfare status of farmed animals, including fish. The original method for measuring Hb, best known as the Drabkin method, is not well suited for work outside of a laboratory setting. I t is time consuming, contains hazardous cyanide elements and requires specific laboratory material. As an alternative to the Drabkin method, portable analyzers have been developed to measure Hb in human blood. For example, in 1982, the Swedish company HemoCue developed a time-saving analyzer, the Hemocue Hb 201+, that measures human Hb within 10 minutes, using coated cuvettes. While this device was proven accurate and validated rapidly for mammalian blood , it was not until recently that this methodology was validated for fish blood. It has been shown that a correction factor i s needed to account for the differences in blood composition between fish and human blood, when using this device to measure Hb in fish blood . In 2019, HemoCue launched a new portable analyzer , the HemoCue Hb 801. In comparison to the Hb 201+, this device uses uncoated cuvettes and takes less than 1 second to analyze Hb , making it even more efficient and suitable for field work.
In this study, the performance of the new HemoCue Hb 801 portable Hb analyzer was compared to the validated Drabkin method in three fish species important for the Swedish aquaculture industry (rainbow trout, Onchorynchus mykiss , Atlantic wolffish, Anarhichas lupus and Nile tilapia, Oreochromis niloticus) .
Hb readings were not different between the two methods for any of the three species (Figure 1) . Hence, we concluded that this new portable device can be measure Hb in fish blood. Unlike the previous model from HemoCue, the Hb 201+, the Hb 801 does neither need an incubation time nor a correction factor for fish blood. This represents a major gain of both time and precision, especially in settings outside of the laboratory.