A needle-type biosensor system was developed for rapid and simple determination of glucose levels in fish blood. The sensor comprises a
needle-type hollow container (18-gauge needle), immobilized enzyme membrane and optic fiber probe with ruthenium complex. The enzyme
membrane was prepared from glucose oxidase, azide-unit pendant water-soluble photopolymer and an ultra-thin dialysis membrane. The optic
fiber probe was inserted into the rolled enzyme membrane placed in the needle-type hollow container. The calibration curve was linear for glucose
levels in fish plasma. One assay was completed within 3 min. A good reproducibility was observed for 60 times without exchange of the enzyme
membrane. The sensor was inserted into the caudal vein of fish to measure blood glucose levels. The sensor responded immediately after insertion
and glucose levels could be monitored. Good correlations were observed between values determined using the sensor and conventional methods
in the range of 48–157 mg d