Possible Clues:

• Schubert's work distant by a mile - fishy business
• Breeding establishment where swimmers are spotted
• Where fish are bred
• Its owner is sure to feed the fishes
• Fish-rearing concern
• Run into black-marketeer, fellow with a jolly fishy business
• Where to see the beginning (and end) of the rainbow
• Peddle miles round Romania by noon for growing business
• Business scaling fry up?
• Fishy business in 3 down is a growing enterprise