Did Medieval Castles Keep Crocodiles in Their Moats? No.

Despite legends and Hollywood tropes, there’s no historical evidence that European castles stocked their moats with crocodiles. Moats were typically filled with water (or left dry) as a physical barrier; introducing large, dangerous reptiles would have been impractical, expensive, and hazardous to the garrison.

Crocodiles appear in medieval bestiaries as exotic curiosities, but they were never a standard defensive feature.