Aquaculture 1 Core fibre 1 Creatinase 1 Creatinine detection 1 Enzymes 1 Evanescent fields 1 Localised 1 Optical fiber fabrication 1 Optical fibers 1 Probe-based 1 Probes 1 Refractive index 1 Resonance technique Reusability 1 Sensing probe 1 Sensor probes 1 Structure-based 1 Surface plasma resonances 1 Surface plasmon resonance 1