The Ancient Arowana is a fairly rare fish in Zelda Tears of the Kingdom if you don’t know where to look! Luckily, there are two specific spots on your Hyrule map that will allow you to find one easily.
What is the ancient Arowana used for?
No, there is no museum to complete like in Animal Crossing, rest assured. However… You will probably want to photograph one of these creatures to obtain it in your Encyclopedia. In any case, the ancient arowana is a fish useful for preparing dishes but especially for repairing your Zora Armor. When you arrive at the estate, Sidon’s companion will ask you for this resource before giving you your beautiful armor which allows you to go up the waterfalls, no less.
This step is essential if you want to continue the main questline of Zora’s Domain.
Where to find ancient Arowana?
The easiest way is to go back to the island of the beginning ! The famous sky island of the Prelude. (Use the teleport points on your map to get there easily). Teleport to the Nacho Yaha shrine and, upon exiting, throw yourself into the void. Head towards the small ponds to the right and north of this area (they are floating islands). You will find fish quite easily in these bodies of water: they are dark gray with yellow fins.
Otherwise, you can find some at the location that Blacksmith Zora tells you: at the end of Mipha Parkjust above the eastern reservoir. To access this area without the armor, you can start from the very bottom, in the reservoir and use the large blocks that come out of the mountain by Infiltrating them!
