The Freshwater Goby, Rhinogobius giurinus, is a rare river fish that can be found between 4pm and 9am, year-round. Despite its rarity, it only sells for 300 Bells.
An information board in the aquarium will provide information about this fish.
"These short and stocky river-dwelling fish have a lot of slender teeth for tearing apart other fish. Freshwater gobies dig holes under rocks in riverbeds to make nests for eggs, which the males guard. Other fish breeds take advantage of this protective quality and often lay eggs in goby nests."
In real life
The Barcheek Goby is a kind of migratory fish, but can also survive and reproduce in a completely closed drainage system. These fish are native to different parts of Asia, including but not limited to China, Korea, Japan, Taiwan, and Vietnam, but has also been introduced into Singapore. They live in rivers, reservoirs, ponds, and estuaries.
Barcheek gobies feed on aquatic insects, invertebrates, small fish, zooplankton, phytoplankton, and dead plant matter.