From Nookipedia, the Animal Crossing wiki
Donating to the museum
Blathers will say the following once the fish has been donated to the museum.
In Wild World
"The clownfish usually finds solace within the fronds of an anemone, wot? These fish are fairly hearty and easy to breed, so they're quite common. If you're going to raise one as a pet, I recommend that you buy an anemone with it!"
It can be found in the ocean tank at the back of the aquarium, swimming in the area around the anemones on the left side of the exhibit.
In City Folk
"Clownfish go hand in hand with sea anemones, wot? A single clownfish family will take up residence in each sea anemone. Occasionally the clownfish will share some of its food with its landlord... All in all, it's a wonderfully amiable little fish who really knows how to treat its neighbors!"
In New Leaf
"Clown fish spend their lives hiding among the feelers of sea anemones, a place only they can live. Their homes may be dangerous, but they produce a special coating that protects them from the poison. In exchange for the anemone's protection, the clown fish chases off any parasitic bugs and enemies. Curiously, all clown fish are males when they're young but change into females if necessity demands."
Chip will say this when given a Clownfish:
Clownfish are native to Indian and Pacific water and can be found in the Great Barrier Reef and the Red Sea. It is usually paired with the Surgeonfish and Butterflyfish, sharing tropical and reef aquariums. The species of clownfish featured in the Animal Crossing series is the common clownfish (Amphiprion ocellaris) which is the most recognizable clownfish and the one most likely found in aquariums. They are usually peaceful, but have been known to attack each other. As mentioned by Blathers in City Folk, it holds a strong bond with a sea anemone, using it as a home and place of shelter. Although the sea anemone is toxic, it fails to poison a clownfish, because the clownfish has a mucus lining on its skin that protects it. The clownfish and the sea anemone feed each other respectively, with the clownfish feeding on undigested matter left by the sea anemone and the sea anemone eats what the clownfish excretes. Wild clownfish are very rarely caught to be used in private and public aquariums; they are now tank-bred, which insures they are more immune to diseases and less stressed when introduced to aquariums.
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