Alaska Blackfish (Dallia pectoralis) is a species of freshwater fish in the esocid family (Esocidae) of order Esociformes. It inhabits Arctic regions of  Alaska and eastern Siberia. They typically live in the densely vegetated areas of lowland swamps, ponds, rivers, and lakes. They are rather sluggish, bottom-dwelling fish that use their large pectoral fins to paddle slowly about the vegetation in search of food. Once a prey organism is spotted, they capture it with a quick dart, much like a northern pike.

When they catch prey, Alaska blackfish are known for their “chunky” texture and taste. Alaska redfish are also capable of catching small fish, but their larger relatives are better adapted for eating larger fish. The Alaska king and Alaska sea lamprey are much larger than their relatives.

The bottom-dwelling Alaska blackfish is one of the few species of fish in the world that are able to breathe air using a modified esophagus. Along with the ability to “breathe” atmospheric oxygen, the Alaska blackfish can also survive in waters with very low dissolved oxygen levels. This helps the blackfish survive winters in areas with less oxygen in its water. The black fish is the only fish species that can survive a complete lack of oxygen. It is a species found in Alaska, British Columbia, Canada, and in several other countries throughout the globe. Alaska is home to the largest population of blackfishes.

Description

Alaska blackfish are small, with an average length of 108 mm, but have been known to reach 330 mm, The head is broad and flat, with the trunk being long and slender. The color is dark green to brown on the dorsal side, pale below, with light-colored blotches appearing laterally. When alive, they usually have a white stripe running along the side of the back, and the head and tail are gray-white. Spawning is common, taking place in the spring and summer. This fish is susceptible to parasites, such as the tapeworm and Sphaerobothrium.

Males can be distinguished from females by the presence of a reddish fringe along the dorsal, caudal, and anal fins; also, the tips of the ventral fins extend beyond the anal fin in males, whereas in females they do not. The presence or absence of red coloration along these fins is consistent with the males of most species being asexual, which is also the case in all three species of Spermophilus.

Habitat

Alaska blackfish are found in highly vegetated swamps and ponds, occasionally residing in rivers and densely-vegetated lakes, where in summer, water is frequently stagnant. Spawning migrations are limited to inshore and upstream movements in the spring, and reverse migrations to deeper water in the fall.

Alaska blackfish navigating through its habitat

When breeding, adult fish can reach up to 5.5 meters (18 ft) in length. Blackfish have an orange-red, fleshy body, a white belly and an olive-green dorsal coloration.

What they feed on

Aquatic insects and other small invertebrates are the principal foods of most Alaska blackfish. However, the larger blackfish are cannibalistic and feed on their own kind; they also eat small, young-of-the-year northern pike. The most common prey fish are small white perch. A variety of freshwater snails are also eaten. Most Alaska blackfishes feed in shallow water, but some are more successful in deeper areas. In ponds and lakes they will sometimes feed and spawn in stagnant waters, which may also be used as a place of habitat.

Breeding

A female, depending on her size, can release a total of 40-300 eggs at intervals during the spawning period, with the eggs then attaching to vegetation and hatching in a short period of time  . The eggs develop into larvae that are then released. A male, on the other hand, releases a large number of eggs in the hope of fertilising many of them, but he may only lay a small number each season females do not usually expel their entire egg contents in a single event.

Alaska blackfish during breeding process

Uses

Blackfish is use as food for man, an important subsistence fish, can be use for commercial purpose. It can also be a food source for the human or animal. Blackfisks is very healthy, a fish that can withstand all kinds of conditions. These conditions include high temperatures, lack of food, as well as high salt levels.

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