From Nookipedia, the Animal Crossing wiki
The Neon Tetra (ネオンテトラ, neon tetora) is a tiny fish found in the river between the months of April and November between 9am and 4pm. It is the smallest fish in the Animal Crossing series. It is introduced in Animal Crossing: City Folk and it returns in Animal Crossing: New Leaf.
Donating to the Museum
"That metallic blue body! Hoo, that crimson tail! That pristine white belly! ...Now, THIS is what I call a tropical fish! No wonder this fish has the word "neon" in its name, eh wot? One of these should liven up the museum nicely!"
"Neon tetras get their name from the beautiful blue metallic line on their bodies. Although they're shy, gentle fish, surprisingly they're related to the piranha, though very distantly. They have very sharp and narrow teeth, an odd contrast to their beauty. They are delicate fish who tend to be very sensitive to the cleanliness and temperature of water."
Neon tetras are native to backwater and clear water streams in southeastern Columbia, eastern Peru and western Brazil, living in the Amazon river. Neon tetras are a popular aquarium fish, mainly because of its appealing coloration. It has a light-blue back that meets a silver-white abdomen, with a red and blue stripe in between them. It is however, transparent. During the night, when the neon tetra is inactive, it loses its red and blue stripe, which turns silver. There is a slight difference between male and female neon tetras. The males have a straight red-blue stripe while females have a slightly crooked stripe, because of their rounder body shape. Neon tetras can be afflicted by "Neon Tetra Disease" (or NTD), which is incurable. It involves the loss of coloration in the bodies as well as restlessness.
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