Tule perch

Young fish from the Russian River

Hysterocarpus traskii is a freshwater fish of the family of the surf perch ( Embiotocidae ). He lives in Clear Lake, in the Sacramento River and the San Joaquin River in California's Central Valley, as well as in the Russian River and the Salinas River west of the California coastal mountains. Hysterocarpus traskii is the only species of the genus Hysterocarpus. The genus name is derived from the Greek " hystera " for uterine and refers to the viviparity of Art The Art epithet was named in honor of JB Trask award, which caught the type specimens and sent to the American naturalist and ichthyologist William P. Gibbons.

Features

Hysterocarpus traskii is 15 cm long. The species is high backs and has a small, terminated its mouth. Adult animals often have a pronounced hump between the head and dorsal fin. The coloration is variable. Usually, the back is dark, often with a purplish or bluish tinge. The color of the bottom may be whitish or yellowish. The edges can be patterned with narrow or broad transverse bands or unbanded.

• Fins formula: Dorsal XV-IXX/9-15, Anal III/20-26, pectoral 17-19.
• Dandruff formula: SL 34-43.

Way of life

Hysterocarpus traskii lives on muddy or gravelly soils in lakes and the lower reaches of rivers and keeps mostly to under overhanging plants or between aquatic plants. The species is rarely found in brackish water. It feeds on zooplankton and hard-shelled, ground-dwelling invertebrates. Like all surf perch is Hysterocarpus traskii viviparous ( viviparous ). The sperm of the male is transferred by modified anal fin rays. The mating season is from July to September. The depending on the size of the female 22-83 juveniles born May to June.