Arapaima

The Arapaima is an fish that can be found in the river. It appears from July to September. It will appear from 4PM to 9AM. When selling it to Re-Tail, the player will earn 10,000 Bells.

Location
The Arapaima is found in the river.

The Museum
The Arapaima can be donated to the museum. Upon doing so, the following text is given by Blathers:

"Arapaima, at over two yards long, are one of the largest freshwater-fish breeds in the world. They've been around for over 100 million years, making them rather ancient fish as well. They breathe through gills but also with an air bladder used by poking their mouths above water. They have hard,coarse tongues that are used to break down the smaller fish they eat."

Quote
Upon catching the fish, the player will say the following:

"I caught an arapaima! And it looks like it's in its prime-a!"