Sturgeon

The  is one of sixteen(16) different fish that can be caught, and either processed for cooking or sold to the Lighthouse Keeper. It's thought to be a relatively high-tier fish, thus the difficulty in catching it is high.

Fishing
The odds of catching a fish are affected primarily by the other fish in the area at that time. More competition means your chance of catching a particular fish over another is lowered. Below is a table of this fish's preferences by the bait used, the place you choose to fish, where you choose to cast, the rod you use, and the time of day.