The existence of fishbone fluctuations at frequencies comparable with those of Geodesic Acoustic Modes (GAM) and Beta induced Alfvén Eigenmodes (BAE) has been demonstrated theoretically in a recent work. Here, we show that observation of fishbones at unexpectedly high frequencies in JET is well interpreted as experimental evidence of high (GAM/BAE range) frequency fishbones and discuss the insights concerning both supra-thermal particles as well as thermal plasma properties that can be obtained from experimental observations.