Freshwater goby

The Freshwater Goby (ドンコ, Donko) is a rare fish that can be caught in the river in every game. It has a small shadow, and it appears all year round. It can be caught between 4 PM and 9 AM.

In Animal Crossing
"This is one of those fish that seem to mysteriously disappear from time to time. Drives fishermen batty, wot! Have no fear, dear friend! You're leaving this beauty in very good wings, hmmmm? Hoo! Owl humor. Hoo hoo!"

In
"A friend of mine claims that freshwater goby tastes fantastic on pizza. What a loon, eh wot?"

In
"This round little fish may look like a mild-mannered goby at first...but it's actually quite aggressive. The freshwater goby is known for its tendency to try to eat anything that will fit in its mouth... Rather shocking, really. I'm quite glad this little piggy's mouth is nowhere near owl-sized, eh wot?"

After donation, the freshwater goby can be found in the middle-left tank.

In
An information board in the aquarium will display this description of the freshwater goby after donation:

"These short and stocky river-dwelling fish have a lot of slender teeth for tearing apart other fish. Freshwater gobies dig holes under rocks in riverbeds to make nests for eggs, which the males guard. Other fish breeds take advantage of this protective quality and often lay eggs in goby nests."

In
"The freshwater goby is an unassuming specimen. But beneath that calm, fish exterior, true gluttony resides! It will eat anything that will fit in its mouth...And its mouth is quite the gaping maw, so I recommend you refrain from drawing attention to yourself!"

Real-world information
The freshwater goby is typically a native fish to tropical and temperate areas of Asia.