Maybe 10 cm long. Incredibly fast moving in the very shallow water, mostly just saw the bubbles/water movement after it had moved. Understand if it's not enough to properly ID.
Its a pretty good and identifiable picture for a photo of a fish. They are difficult to photograph for a number of reason including that auto focus usually picks the substrate or the surface, They are also pretty fast and the reflective index of water means that they are hard to get a clear picture. So well done on that one.