Goldfish

The Goldfish is one of the smallest fish. Despite its tiny size, it is actually quite rare. It can be found in the river. It has a tiny shadow and is 15 centimeters long. It sells for the relatively high price of 1,300 Bells. Like it's cousin the Popeyed Goldfish it appears within a Goldfish Bowl when placed in the house.

Donation to the Museum
As with all fish and bugs in the series, the goldfish can be donated to the Museum by talking to Blathers, who will tell the player a little bit about the donation.

In Wild World
This is Blathers's speech about the newly donated fish:

"Hoo, in my youth, I once had a goldfish in my room. His name was Sir Blathers. Goldfish are actually quite sociable creatures, eh wot? At least they are when they're being fed, that is. Who can resist them?"

It appears in the first tank in the aquarium.

In City Folk
Blathers will say this when handed the fish in the museum:

"Hoo now... Do you know how large goldfish can get? Well, they can grow up to... ONE FOOT LONG! The growth of a goldfish in a tank is inhibited by tank size, so you rarely see them that big, I'd imagine. Even so, our tanks here at the museum are spacious... so expect our new goldfish to make a BIG splash! ...Hoo now? Not at all funny, you say?"

It can be found in the small tube-tank in the aquarium.

In New Leaf
It has been confirmed that the goldfish reappers in New Leaf

Placing in a Room
When placed in the house it swims in a blue-rimmed bowl with seaweed instead of the typical Fish Tank. The reason is because goldfish are famous for being kept in glass bowls instead of the rectangular tanks.

Encyclopedia Information
Once the player has caught a particular fish or bug, they can find information about it in the bug or fish menus. Once the goldfish has been caught, the following information can be found in the fish menu:

Further information
The goldfish featured in Animal Crossing is the Fantail breed, which is the western variation of the Ryukin ("Dragon family") breed. It has two fins instead of one, an egg shaped body, a high dorsal fin and lacks a shoulder hump. They appear to have a distaste for cold waters. These, like all goldfish, are commonly kept as pets, and prefer a water temperature of 13 - 21 degrees Celsius/Centigrade.

They are proven to be very closely related to the Crucian Carp, and despite what is often thought, it is not bred from this species. Instead, the goldfish known is actually bred from a dullish silver fish found in Japanese rivers (Crassius auratus), which is actually called the goldfish, due to the fact that it was known to occur in a gold-yellow morph naturally.

Around 600-900 they were popular in garden ponds, where they were put together with other carp species. The gold morph has become more abundant due to the major preference of this colour over the more common (at least in the wild) silver colouration.

Goldfish have been bred into a wide array of shapes, sizes and even colours, as seen on the Telescope Goldfish breed.