Gar

The gar is a fish you catch in ponds. Look for a very large shadow. In the northern hemisphere look for it in Jun – Sep, from 4 PM – 9 AM. It can only appear after you have caught 50 fish. Nook's Cranny pays 6,000 Bells, C.J. pays 9,000 Bells.

An X-Large pond shadow from late afternoon until morning, after 50 catches. Ponds are small, so throw bait in to cycle shadows until this 6,000 Bell catch shows up.