First listen and then answer the question.
What kind of fish are they?

    Fish and chips has always been a favourite dish in Britain, but as the oceans have been overfished, fish has become more and more expensive. So it comes as a surprise to learn that giant fish are terrifying the divers on North Sea oil rigs. Oil rigs have to be repaired frequently and divers, who often have to work in darkness a hundred feet under water, have been frightened out of their wits by giant fish bumping into them as they work. Now they have had special cages made to protect them from these monsters. The fish are not sharks or killer whales, but favourite eating varieties like cod and skate which grow to unnatural sizes, sometimes as much as twelve feet in length. Three factors have caused these fish to grow so large: the warm water round the hot oil pipes under the sea; the plentiful supply of food thrown overboard by the crews on the rigs; the total absence of fishing boats around the oil rigs. As a result, the fish just eat and eat and grow and grow in the lovely warm water. Who eats who?