Goldfish Cauliflower

[haowin]

dont know if im spelling it right, but one of my goldfish has a cauliflower like white growth coming from its left gill. whilst doing a substrate change i moved the fish into a bucket. But when i was about to put it back in the tank i saw the abnormality. Its in a tub atm.
Any help thanks

 

[haowin]

It seems since in the time ive written this and done some research, the majority of it has fallen off.
Its still got some remaining along the edges of its fin and gill.
Cant take any pictures of it. cant make out the white growth.
Anyone know what it is, or what to do? feel kinda sick on the fish, just sittin in a tub