- "I caught a sweetfish! Hmmm. I've had sweeter!"
An information board in the aquarium will provide information about this fish.
"Sweetfish are migratory fish born upstream that travel to the ocean and then return to rivers to spawn.This migratory mind-set is what emphasizes their similarity to salmon. Adult sweetfish have a watermelon-like mossy smell when caught, since they eat moss on riverbed rocks. Sweetfish are very territorial and will attack rivals that encroach on their territory. Anglers use this combative nature against them by using lures made of other sweetfish."
In real life
The Ayu, or Sweetfish, is an amphidromous fish. It is a relative of the smelts. It resides in rivers, lakes, and coastal waters of western Hokkaidō in Japan southward to the Korean Peninsula, China, Taiwan and Hong Kong. The name “sweetfish" comes from the sweetness of its flesh. It is also referred to as the “year-fish", in reference to it’s one-year lifespan.
The Ayu’s diet consists of algae, crustaceans, insects, sponges, and worms. They are also very territorial. Ayu is an edible fish, mostly consumed in East Asia. Its flesh has a sweet flavor, with “melon and cucumber aromas".