Magnets Or Skill?

I would say the "fish tank" is the biggest clue in this clip. Some people have suggested they fed the fish iron, or implanted it and it's done by magnets underneath the shallowest fish tank that was ever built. Fish are also quite clever too, shadows are the enemy to anything living in water so they could be manipulated that way too. Judge for yourself.

It's better than that Scottish bloke in the 80's who used to swallow a poor wee goldfishy and boak up two.