The maximum body length is 61 cm, and the mass is up to 2.1 kg [3] . The maximum reliably recorded age is 18 years [4] .
Dorsal fin with a notch separating the prickly part with 21-22 rays and the soft part with 24 rays. In the anal fin there is 1 prickly ray and 23-24 soft rays. The pectoral fin contains 18–20 rays, separated by wide dissected membranes. Caudal fin rounded or truncated. There are paired earlobes behind the eyes and on the back of the head. Five lateral lines run along the sides of the body; the first reaches the back of the dorsal fin, the next three extend along the entire body, and the latter bifurcates between the ventral fins and the anal fin [1] .
Males and females look so different that at first they were described as different species. Body color in fish of both sexes varies from light gray to brown. In males, numerous blue or blue spots of an indefinite shape are scattered throughout the body and head, around which there are small red spots. The color of the females is monophonic with small dark dots [5] .
It is found only in the northeastern Pacific Ocean from the Aleutian Islands and Alaska Bay to southern California .
Coastal bottom fish lives at a depth of 1 to 46 m near rocks and reefs over rocky and sandy soils, often in thickets of aquatic vegetation. Leads a sedentary solitary lifestyle, performs only seasonal spawning migrations [1] [5] .
Spawning periods vary in different parts of the range . In California, spawning occurs in December – February, in Puget Sound Bay and British Columbia in late autumn, and in Alaska in August – September [6] .
For spawning, they approach close to the shores, males begin spawning migration earlier than females, choose spawning territory and begin to guard it. Portion spawning, the female makes several clutches; in some cases, in one clutch there may be caviar of several females [7] . Caviar is laid on rocky ground covered with fouling (periphyton), on aquatic vegetation, sometimes in empty shells of a giant marine acorn ( Ballanus nubilis ). Adhesive eggs with a diameter of 2.2-2.5 mm are attached to each other, and the total mass of eggs is attached to the ground. In the clutch of 1500-9600 eggs. The size of the masonry reaches the size of a tennis ball. Caviar in the masonry is blue with various shades at different stages of development. Eggs contain numerous small yellowish-orange fat droplets [8] .
After spawning, the females immediately migrate to the feeding grounds, and the males, after fertilization of the eggs, protect the clutch up to the hatching of the larvae. One male can guard several clutches. If for some reason the clutch is not guarded by the male, then all caviar is eaten by predators [5] [6] .
Embryonic development lasts 4-5 weeks. Often over time, the masonry is covered with diatom epiflora . Larvae and juveniles under the age of 1 year live in the pelagic zone , spread over currents over considerable distances (sometimes up to 500-600 miles from the coast), then go on to a benthic lifestyle [1] [8] .
The larvae and juveniles of the American rasp feed on zooplankton . During the breeding season of mass fish species (for example, Pacific herring Clupea pallasii ), juveniles can switch almost entirely to feeding on eggs and larvae of these fish. In adults, the spectrum of food organisms is very wide, the diet includes amphipods , isopods , gastropods , polychaetes , shrimps , crabs , mollusks and small fish [5] .
Feed organisms are consumed by suction with a stream of water created by a change in pressure in the oral cavity. The degree of pressure change can be regulated depending on the type of victim [9] .
Many species of bottom fish feed on the youth of the American rasp, while adult individuals are subjected to the press of predatory species, such as a toothy rasp and common seal .
Specialized fishing is not carried out, it comes in the form of by- catch in the trawl and longline fishery for toothy rasp and other bottom fish. Often comes across when fishing from the coast or small boats in the coast. A favorite object of spearfishing .
