From Nookipedia, the Animal Crossing wiki
The Giant Snakehead (ライギョ, Raigyo) is the daytime counterpart of the Gar. They can be sold for 5,500 bells in Animal Crossing: Wild World, Animal Crossing: City Folk, and Animal Crossing: New Leaf, and 6,500 in Animal Crossing. They are found between 9 a.m. and 4 p.m., from June to August.
Donating to the Museum
In Animal Crossing
"What a stupendous beast! It must have taken great effort to land this fearsome creature, eh wot? I've heard that giant snakehead carry parasites. Be sure to throughly cook them before eating. Blech! Parasites! Of course, we'll accept this one. Have no worries, we'll take special care of it.
In Wild World
"I firmly believe the best way to prepare a fish is the way the locals do it... Based on that philosophy chili-pepper flakes are a must with giant snakehead! And if you notice one shaking chili flakes On YOU, might I suggest fleeing?"
In City Folk
"...What a giant snakehead! These fish are notorious for their tremendous appetites, eh wot? Much like a snake, once one of these grabs its prey, naught can convince it to let go... I should think a few well-placed owl kicks might convince it, should one ever take a liking to me! In any case, this fish doesn't hunt all year 'round. It hates the cold and hibernates through winter. I've come up with a smashing nickname for it... "The Scourge of Summer!" Marvelous, eh wot?"
After donation, the giant snakehead can be found in the big, left-hand fish tank with other river fish.
The giant snakehead is the largest in the family Channidae, capable of growing to over one meter in length (three feet) and a weight of over 20 kilograms (40 pounds). They are predators, and they can consume organisms ranging from small fish to other snakeheads.
Names in other languages