VISUALIZING THE WATER-FLOW IN A BREATHING CARP USING NMRI

The study of water flow inside the fish mouth and opercular cavities h as been hampered by the lack of a non-invasive measuring device. Measu rements of the water flow during breathing of a carp are presented her e, using a non-invasive technique, Nuclear Magnetic Resonance imaging (NMRi). Using NMRi, velocity profiles in a whole slice of the fish can be measured at once. The present results, which represent the average flow pattern during a breathing cycle, confirm literature data of an elongated volume of moving water in front of the mouth of the fish. Fu rthermore, it is observed that in the narrow spaces between the hemibr anchs the water flow remains fast. Suggestions are given for improveme nt of the experimental set-up, such that more detailed and complete da ta of the flow in the fish mouth and opercular cavities may be obtaine d.