From Nookipedia, the Animal Crossing wiki
The Crawfish (ザリガニ, Zarigani) is a common crustacean found in the Holding Pond from April to the middle of September, found at any time of the day. Despite its crustacean species, it is classified as a fish. It is worth 200 Bells.
Donating to the Museum
Blathers makes these statements when the Crawfish is donated to the museum.
In Animal Crossing
"This diminutive fellow is a relative of the lobster. It's pincers are small, but distressingly powerful, wot? Indeed, it delights in a little pinchy-pinchy, eh wot? We'll take pains to ensure our mutual safety."
In Wild World
"You'll find these little fellows in many pots across the southlands, I imagine. I've personally never sampled one. They look rather... insect-ish. Blech."
In City Folk
"...I don't do particularly well when around crawfish. I mean, really. Look at it. It's like a wretched insect! And those legs... Did you notice all those wiggly legs? All the better to revolt me. Hoo, and the vulgar belly, all segmented and buglike. Absolutely abhorrent!"
It can be found in the middle-left tank in City Folk.
In New Leaf
"These shrimp relatives are usually found in ponds and rivers, typically making them easy to catch. The reason for this strange habitat is that crawfish are plentiful and will eat just about anything. Eating plant material makes their bodies red, but only eating fish and meat will turn their bodies blue. A red color indicates they are eating a healthy and balanced diet, so red is the ideal for the species."
Names in other languages