I spent most of a summer staying with other astronomy students at Herstmonceux Castle, then the site of the Royal Greenwich Observatory. The observatory staff lived outside the castle in the nearby villages, so we were the only residents apart from the Astronomer Royal, Sir Richard van der Riet Woolley, and had pretty well the run of the castle.
We were fascinated by the carp which inhabited the castle's moat. They were large and docile. If we dropped snacks of food from the drawbridge, the fish would rise in a heaving shoal, climbing over each other's backs on the surface to snatch each morsel. We had no fishing gear, but we tied a chip to a piece of string and were amazed to see it greedily devoured. The string sped away until it ran out, whereupon it came free with no chip and no carp. Then we conceived a novel fishing method. We weighted a wicker waste-basket with stones, and lowered it into the moat with strings on each side. We tossed digestive biscuits onto the surface above it, waited until the heaving mass of fish struggled for them, then hoisted it aloft.
Alas, the fish were too smart. We caught a couple, but they leapt clear as we pulled the basket upwards. We resolved to perfect our technique the next day, but a note from the Astronomer Royal appeared, ordering us to desist from disturbing the moat's residents, so the carp were left in peace.