Visualising the Water Flow in a Breathing Carp Using NMRi

Abstract

The study of water flow inside the fish mouth and opercular cavities has been hampered by the lack of a non-invasive measuring device. Measurements of the water flow during breathing of a carp are presented here, 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. Furthermore, it is observed that in the narrow spaces between the hemibranchs the water flow remains fast. Suggestions arc given for improvement of the experimental set-up, such that more detailed and complete data of the flow in the fish mouth and opercular cavities may be obtained.