Brazhnikov's Killer Whale (Pelteobagrus Brashnikowi)

Brazhnikov's killer whale, or blue killer whale, or small killer whale is endemic to the Amur River. Inhabits freshwater lakes, oxbows and channels with a quiet current. In the wild, it feeds on various chironomid larvae. Leads a twilight lifestyle. Spawning is portioned, in the riverbed, in areas with a quiet current near a steep bank at a depth. Kept in aquariums by some hobbyists.

Photo by Lukina Elena

Description

The body is slender with a long and thin caudal peduncle. There are 4 pairs of antennae. The adipose fin is noticeably shorter than the anal fin. The caudal fin is two-lobed. The spines of the pectoral fins are serrated only along the inner edge. The dorsal spine is strong, equal in length to the pectoral one, not serrated posteriorly. The sides of the body in front are covered with very fine villi. The head is covered from above with thick skin through which the bones are not visible. The mouth is small; the upper jaw protrudes strongly over the lower. The lips are thick. The teeth on the jaws and palate are very small, densely set. The eyes are covered with skin. Branchial stamens 9-12. Anal fin with 22-24 rays.

Area

Russia (Amur, Sungari and Ussuri rivers, Khanka lake), Northwest Korea, China (Heilongjiang, Jilin).

Habitat

Inhabits freshwater lakes, oxbows and channels with a quiet current. Winters in the Amur riverbed and in deep channels. There are almost no fish in the riverbed.

Related article Squeaky Killer Whale (Tachysurus fulvidraco)

Color

The main background is light yellow, with irregular dark spots on the sides; the ends of all fins are dark, the belly is light. The dorsal fin is dark, the rest are light.

Dimensions

Up to 20 cm, weight is usually up to 100 g, maximum weight - 380 g.

Life span

Usually, the life span of the Brazhnikov killer whale does not exceed 5-10 years.

Nutrition

In the wild, Brazhnikov's killer whale feeds on various chironomid larvae. In aquariums, he takes live (aquatic invertebrates) and combined feed. Fish feeding was not noted. Juveniles feed on pelagic crustaceans.

Lifestyle

Brazhnikov's killer whale leads a twilight lifestyle, very actively moves in the water column. In autumn it enters the Amur bed and its deep channels.

Reproduction

Spawning in batches, at the end of June - July, in the riverbed, in areas with a quiet current near the steep bank at a depth of 0.6-1.0 m. Fecundity is up to 1-2.7 thousand pale green eggs with a diameter of about 2.3 mm. The caviar sticks to the roots of washed-out terrestrial vegetation. Larvae hatch in 2.5-3 days with a length of 5.3 mm. At first, the larvae are photophobic and hide at the bottom, near the spawning grounds. On the 7th day, at a length of 8.9 mm, the yolk sac is absorbed, and the larvae begin active feeding.

Puberty

Males reach maturity in the 3rd year of life, with a length of 12 cm.

Economic value

Brazhnikov's killer whale is a species of little value and in some places is even harmful, as it clogs the nets, catching on fin spines. Used as an aquarium fish, it lives well in captivity, but does not reproduce. They use earthworms and dung worms, semolina, bread, maggots, bloodworms and caddisflies as bait.

Keeping in the aquarium

Dimensions: an aquarium with a volume of 100 liters.

Water: water hardness does not matter, pH is about 7, aeration, filtration. Weekly water changes up to 30%.

Temperature: 16-28 ° С, in winter it can drop to 4 ° С. At temperatures below 10 ° C, fish stop responding to food and move, their color darkens.

Lighting: diffused.

Soil: coarse river sand or fine rounded gravel.

Plants: live plants.

Decoration: various shelters - driftwood, grottoes, stones, pipes.

Related article Siamese killer whale (Pseudomystus siamensis)

Personality: peaceful. Brazhnikov's killer whale prefers to swim in the current, only occasionally hiding in shelters.

Water zone: bottom layer of water.

Not to be kept with: small fish.

Breeding orca Brazhnikov in the aquarium

To stimulate reproduction, the water temperature begins to gradually decrease from 22 ° C to 4 ° C for three weeks. After a month's "wintering" increase by 1 ° C every day, every two days making a change of 20-25% of the water volume. Spawning fish with a volume of 300 liters, spawning in thickets of aquatic plants, the walls of the aquarium are covered on three sides with paper. Water parameters: dH 5.4 °, pH 7.5-8.0, T 25 ° C. The male digs a nesting hole. Spawning is usually morning. The marks are repeated after six to seven minutes. After spawning is complete, the male drives the female away, and he himself remains to guard the nest.

Sex differences: the male is larger than the female, its spines are more massive. The female is fatter than the male. The color of the abdomen in the male is lemon yellow, and in the female it is dirty yellow.

Number of eggs: up to 3000 pale green sticky eggs.

Incubation period:depending on the water temperature - 2-3 days.

Offspring: fry swim for 3 days. Larvae don't like light. The fry are gregarious, during the day they keep in shelters, and only in the evening they leave the shelters and begin to hunt.

Growth rate: fast - up to 1.5 mm per day.

Feeding juveniles: starter food - zooplankton, at the age of two weeks - tubifex, at three weeks they give bloodworms.

Jumping from parents: the female is jigged after spawning.

Comments: Since the Brazhnikov's killer whale has strong thorns, it is necessary to handle the fish very carefully.