we got pond goldfish a month ago, and 1 fish has some gammy mouth like something is stuck in it or growing from it. What do people think we should do? We haven't actually seen it since the first poorly morning i saw it.

We've been training as suggested on the tetra packaging, and the majority of fish have been coming up to see us.

Is it a grey/white colour?

I had a goldfish that got a pebble lodged in it's mouth a few times. I had to pick it up, and carefully get it out with a knitting needle.

If it's white and like cotton wool then it could me mouth fungus and you'll need to buy a cure for it in an Aquarium shop.