I have a goldfish that most people can't stand to see because he has a black tumor of some kind on his back. 
Poor little Quasimodo. 
But I love this goldfish. I once came home to find him gasping at the bottom of the tank. 
I thought that his time had come. The tumour had got him, but no. 
As I reached in to lift him up I saw the problem. 
It isn't the first time I've saved a fish's life. 
He - as many fish which love to eat do - had sucked on a pebble so hard that it got stuck in his mouth. 
I kid you not!
          
        
I pried the pebble from his mouth with a little lever and let him be. 
He floated for an hour in a corner on his side -  had been too late? 
But he was soon on his friendly, happy way. 
He doesn't grow as big as the other fish. 
 
Nobody believes that I saved his life of course. 
But it's the second time I've conducted this operation on a fish. 
 
Today he seemed to be turning somersaults as he fed off the bottom and juggled his burden. 
If a pebble doesn't get Quasi I'm afraid that the tumour will.