From Nookipedia, the Animal Crossing wiki
The black bass (ブラックバス, Burakku basu) is a common fish found in the river. It appears year round, all day, and sells for 300 Bells. Despite the name, the black bass is a dark shade of green. It is a member of the bass family.
Donating to the museum
In Wild World
"In sport-fishing, the black bass is very often the main quarry... It's apparently a delicious fish, so I'd imagine some sport-cooking follows! Indeed, I suppose they would call that a catch-and-eat program! Hoo hoo!"
In City Folk
"The black bass sports tremendous strength for its size, making it a popular catch in sportfishing. The bass is so popular that there are even fishermen who specialize exclusively in catching bass, eh wot? There are concerns about the effect of fishing on its habitat...but even so, this fish remains a favorite."
In New Leaf
Once the fish is donated, Blathers writes the information on it on a corresponding board in the museum.
"They get their name from their somewhat blackish bodies, though they have a green tint. They usually hide in weeds and wait until other fish approach before forcefully striking. Many people use lures to catch black bass because they are such strong fish. Black bass have a fierce image, as the males will scare off other fish to protect the fry in the nest. They are related to sea bass, so they make for a tasty dinner, though their skin has a very strong odor."
The black bass is native to the Southern United States and comes in three varieties, by frequency: the Largemouth bass and Smallmouth bass followed by the rarer spotted bass. It has become one of the most popular fish for fishing as a sport, especially in the USA, but around the world, it has been stocked and have been noted to grow to be over 3 feet (1 meter) long. The average one can expect to catch is up to 5 pounds (2 kilograms).
More information on this topic is available at Wikipedia.
Names in other languages