I understand that small fish like whitebait should be cooked in two minutes and anything above is probably overcooking. Of course a better guide is to go by temperature and the fish being opaque.
Well I understand that once the fish is at 145f/63c it is done however this is also the temperature at which those white bubbles(scum?) come out of the fish? Therefore I went with the ide that once the scum starts rising to the top the water the fish is cooked.
To be safe I allowed the scum to rise to the top(which started after 5 minutes of simmering) then switched the heat off and removed the scum. I noticed the water still tastes unusual i.e. perhaps I had overcooked it.
Am I still overcooking it? Why would using the scum rise to the top not be a good way of assuring that the heat reached the required temperature?