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Wednesday, Aug. 27, 2008

ANIMAL TRACKER

Japanese Minnow


Japanese name: Mugitsuku

Scientific name: Pungtungia herzi

Description: Also known as the "striped shiner," this is a small, sparkling fish, growing up to 55mm long. There is a broad black stripe running down the length of the body, and a brown stripe on the back. The lower half and the belly of the fish is silvery white, though in males the belly turns red during the breeding season. The nose is blunt and the scales are small.

Where to find them: All over Japan, from Hokkaido to Kyushu, in clear or slightly cloudy water that's either standing or flowing over stones, silt or sand. Also in streams where they can be seen in schools gathered at the bottom of water riffles as they prefer well-oxygenated water. They also like to forage among the stems of aquatic plants. These are gregarious creatures, and if you see one there are likely to be others nearby — sometimes lots of others.

Food: Pretty much all-rounders, minnows eat algae and other bits of plants they can forage from the bottom of the water, and also aquatic insect larvae. Their small fry make nice snacks for larger aquatic insects such as dragonfly larvae, and for larger fish. Fishermen sometimes use lures made to look like shiny minnows — or even the fish themselves as live bait.

Speacial features: Males make scoops in the bed of the river, and females spawn into these nests from April to September. When this happens, the male guards the female to make sure she is not interrupted while spawning — and that he will be the one to fertilize her eggs. Particularly dominant males may dig several nests, and have a school of females they will attempt to guard. But they have another trick: Females often lay their eggs — like cuckoos do — in the nests of other species. When this happens, the minnow eggs develop very quickly, and hatch before the eggs of the "host" fish. The host male — perch and gobies are favorite dupes of female minnows — will guard the parasitic eggs. Females lay eggs many times during the breeding season, with some producing as many as 6,000. Just before spawning, male fish chase females persistently, rubbing their bodies against the females.

PHOTO COURTESY OF BIO-IMAGE NET



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