Knife fish (the Afteronot family) got its name because of its flat, tapering shape resembling a knife. The habitat of these fish is slowly flowing and overgrown reservoirs of the Amazon River basin (Bolivia, Peru, Brazil, Colombia). In an aquarium, the afteronotus can reach a length of 30-40 cm, and in nature - 50 cm.
Protein-ateronotus (or black knife) has an elongated body, without scales, with a sharp line of the abdomen. In the tail area, they have an organ that emits weak electrical pulses, which allow the fish to defend themselves from enemies and at the same time navigate in troubled waters. He has no ventral and dorsal fins, but the anal one is perfectly developed, which stretches from the head to the tail. Making wave-like movements with this fin and regulating them with pectorals, the fish-knife can move in any direction, and at the same speed (back and forth as well as up and down). The caudal fin is rather small. Color - velvet black, with a white line running along the back. On the caudal stalk - two transverse yellowish-white stripes in the form of ribbons. Females differ from males in smaller sizes and a more convex abdomen. In males, a small fat cone may be present on the back of the head.
The black knife is a peace-loving, even shy fish, characterized by activity at night. The peaceful nature, however, is not an obstacle in the hunt for smaller fish. Knife fish is a predator and prey it serves, in addition to fish trifles, tadpoles, worms, crustaceans. Fish of this species live in muddy water and navigate in it, and even at night, they can, thanks to electrical pulses, as well as receptors located along the length of the body. When moving, the fish-knife creates an electromagnetic field that allows it to feel the prey in any direction.
Aquarium fish-knife for its maintenance requires an aquarium of 200 l and higher with strong aeration, peat filter, water temperature 24-28oC, with a pH of 6-7, hardness 2-10o. They love solitude, so they need personal shelter in the form of snags, decorated tubes or pots. Water changes should be made once a week, up to 35% of the volume of the aquarium. Protein apteronotus is susceptible to ichthyophthyroidism. You should be aware that in the treatment of this disease in no case is it recommended to use preparations that include zinc.
With an aquarium content, it is desirable to create fish conditions that are close to natural. Skirmishes often arise between males, so there should be enough shelter for them. The size of the fish of knives should be taken into account and compared with the sizes of other types of fish: they take small fish for food, and too mobile and aggressive neighbors give them inconvenience. So, afteronotus is absolutely incompatible with barbs, which can cause irreparable harm to them, gnawing off their fins.
Knife fish prefers to feed on live food: insects, tubule, fry of other fish, squid, larvae or shrimp. You can give small pieces of meat. They are reluctant to learn to use artificial feeds, but with a certain effort this can be achieved. The best time for feeding fish is in the late afternoon.
Athertonotuses reach puberty at the age of one to one and a half years. For spawning, 2 males and 1 female are selected. Spawning usually occurs on a stream of water created by a pump with sprayers (they are specially set for this time), in the morning, in the hours before dawn. Fertility of a female can reach 500 eggs. Caviar is relatively large, yellowish, slightly sticky. Spawning occurs in the cracks between stones, snags or decorations. Caviar larvae appear after two or three days, and after 5-6 days they can already swim and feed on small plankton on their own. From the second month, the fry are recommended to provide a sufficient number of individual shelters, otherwise they can bite off the tail stems from each other during the fight.
