Dorado

The Dorado (ドラド) is a golden fish. It is an extreme 100 centimeters long (40 in.), which is long for a river fish. Its name, dorado, reflects its color, as "dorado" is Spanish for golden. This fish and the Stringfish are the most expensive river fish obtainable, selling for 15,000 Bells, beating the Arapaima and Arowana, who are both tied at 10,000 Bells. This fish is diurnal, meaning it is most likely seen from morning to evening, or, more specifically, 4 a.m. - 9 p.m. In, it is the rarest summer river fish in the series. It will appear during the summer, from June to September.

Donating to the Museum
When in the museum, this fish appears in the middle tank and the right tank.

In Wild World
Upon the player's donation to the museum, Blathers will comment on it:

"Hoo my! Congratulations are in order! You've finally caught one, eh wot? Did the mighty dorado put up a good scrum? You've passed the test! You're initiated into the secret club of fisher folk!"

In City Folk
Upon the player's donation to the museum, Blathers will comment on it:

"My hoo, I never dreamed someone in this town would hook a dorado! It's a fish that lives up to the image of El Dorado it conjures... I could gaze upon it all day!"

In New Leaf
"Dorado means "golden" in Spanish. As the name would indicate, these fish are gold and have black dots. They look like salmon but are very toothy, carnivorous, and related to piranha. They're such ferocious fish that other fish regularly flee from them, fearful of becoming a snack. Their ferocious nature and power make them a prize catch among anglers."

Further Information
Dorado is Spanish for golden, a suitable name for such a shining fish. In real life they are frequently confused with the Mahi-mahi, Coryphaeus hippurus (dolphinfish) also called the dorado, which is the name of an oceanic fish that it is unrelated to and does not appear in Animal Crossing. The two real life species of "freshwater" dorado are Salminus maxillosus and Salminus hilarii. This fish can be found in the rivers of South America, most notably the Parana River of Argentina, and its tributaries.