In Animal Crossing: New Horizons (ACNH), fishing is one of the main income sources.
This is a price list of all fishes in the game. An arowana can sell for about 10,000 Bells.
Here’s how you can find an arowana in Animal Crossing: New Horizons (ACNH).
How to find arowana fish
For the Northern Hemisphere, you can find arowana from June all the way to September.
As for the Southern Hemisphere, arowanas will appear from December to March.
They typically appear from late afternoon (4 pm) to morning (9 am).
Also, they will be found in the rivers.
You should be able to catch them on your island. Otherwise, you can try going to mystery islands to hunt for them.