Stringfish

The stringfish is a fish you catch in rivers on the clifftops. Look for a very large shadow. In the northern hemisphere look for it in Dec – Mar, from 4 PM – 9 AM. It can only appear after you have caught 100 fish. Nook's Cranny pays 15,000 Bells, C.J. pays 22,500 Bells.

Search the clifftop rivers for an X-Large shadow from late afternoon until morning, after 100 catches. It is very rare, so throw bait up there; it sells for 15,000 Bells.