My friend has a freshwater tank with 3 fancy goldfish in. Last week the oranda had a kind of bruising around it's eye, and the eye buldging. The eye developed a White film over it which came off this morning together with the whole eye! Is this likely to be the result of an injury or something more sinister? The other 2 fish are currently fine. The affected fish looks fine apart from the eye, no clamped fins, ok it's not as active as normal but it's not just floating. Any advice please? I dosed the tank today with tetra general tonic as a precaution.