Despite the usual opinion that fish spawn, in nature there are viviparous species. And they are not so little. For example, many of the sharks that are also fish are viviparous.
Moreover, viviparous fish can be divided into 2 groups, representatives of which are found among sharks. In the first case, fertilized eggs develop in the mother’s body independently, at the expense of their own nutrients. The baby hatch and for some time is in the body of the mother shark, preparing for an independent, full of danger, life at sea. Scientists believe that in some species, young sharks in the mother’s body feed on unfertilized eggs. This option is called egg production.
The second option, live birth, has a clear analogy with this pregnancy, typical of mammals. A fertilized egg grows against the wall of the uterus and feeds not only from its own reserves, but also from the nutrients supplied from the mother’s blood. Despite the small number of offspring, it is well prepared for independent living and can easily survive on its own.
Classic Black-tailed Sword
Among the bony fish, viviparous is the eelpout. Northern fish living in cold seas, up to 40 centimeters. Almost no industrial value, including due to prejudices about live birth. This kind of little studied. The well-known, commercial, sea bass is also viviparous. The peculiarity of this fish is a large number of small, 4-6 millimeters long, sweeping out larvae, which is not typical for viviparous fish. Newborn fish are small and transparent, keep on the shallow water warmed up by the sun and are almost invisible to predators. Growing up, they are forced to hide in floating plants and snags.
Similarly to aquarium viviparous small fish, spermatozoa are kept alive for a long time in the body of the female sea bass. Mating sometimes occurs several months before the mark. Calf also develops in the mother’s body very quickly. The Baikal golomyanka also belongs to the viviparous. This fish is up to 15. 25 centimeters in size, living at a great depth up to 300. 500 meters in Lake Baikal. As with the sea bass, the number of harvested larvae is very large, up to 5,000 pieces. But it is time to return to the aquarium live-giving fish.
Velifers golden mollies
In aquariums often contain representatives of viviparous toothed. The fish of this family inhabit the waters of the islands of the Caribbean, the northern part of South America and the southern part of North America. Viviparous fish are found in slowly flowing or standing waters, with dense aquatic vegetation. Some species live in alpine lakes with clear fresh water, saturated with oxygen, others inhabit the mouths of rivers near the sea with brackish water.
Under natural conditions, viviparous toothfish feed on insects and their larvae. Representatives of certain species to one degree or another feed on plant food, primarily the lower algae.
Viviparous aquarium fish are the most popular and unpretentious aquarium dwellers, who are the first in many novice aquarists. Often, in the future, experienced breeders again return it to them. Their other advantages are bright coloring and peculiar behavior. The simple conditions of keeping and breeding most of these fish make them indispensable for beginning aquarists, allowing you to get the first experience.
The maintenance and reproduction of viviparous fish is quite simple. High adaptability allows them to tolerate a strong increase and decrease in temperature, very hard water. An aquarium of any size, up to a five-liter jar, is suitable for keeping many representatives of viviparous tooth-bearing ones. For a pair of guppies, it can be a small 5. 6-liter aquarium or a large one, at the rate of 1.5. 2 liters of water for each fish.
The aquarium should be illuminated with a natural, bright light, but if this is not possible, artificial lighting will be suitable. It should be a lot of plants. The bright coloring of viviparous tooth-like underlines the illumination with natural reflected light. Free swimming places and dense thickets of plants resembling a natural habitat enable these fish to develop fully.
Reproduction of viviparous fish is possible even in the general aquarium, with a low planting density, only you need to grow thick, small-leaved and always floating plants, such as salvinia and richcia. Ahead, in the center of the aquarium you need free space for swimming adult fish. The most favorable water temperature for the content of most species is 20-24 °. A guppy, sometimes, can live in an unheated vessel at room temperature.
The composition of the water in the content of these fish is usually not significant. As a rule, it can be hard or medium hard, fresh, just settled and “old”. For fish species that are common in nature in brackish waters, it is advisable to add one tsp of salt per 10 liters of water.
Viviparous tooth-like unpretentious in feeding. Supplementary feeding with vegetable food is useful for them: lettuce, seaweed, crushed oatmeal. They will willingly eat any live food, they will not refuse ice cream, they can grow and develop on dry and combined types of food.
Live birth is the most characteristic and interesting feature of kartozubyh fishes. In most species, males are smaller and brighter colored, while females are larger and more inconspicuous. Males usually have elongated dorsal and tail fins. The anal fin in males for the period of puberty begins to lengthen and turn into gonopodia, which is used during reproduction. Many viviparous gonopodia lively and mobile can take different positions, with the help of special muscles necessary for the implementation of fertilization.
Sperm once in the females are stored there for a long time. Thus, a single fertilization can lead to multiple "childbirth." The ability to produce multiple fry as a result of one fertilization makes the crossing work very difficult. This is especially true of guppies, who after one fertilization have up to 6-8 "genera". The only way to combat this phenomenon is the isolated content of virgin females intended for crossing.
The duration of development of caviar in viviparous, depending on the species, varies widely. from 30 to 50 days, depending on the age of the female and living conditions. At the same time, the female has a clearly visible dark spot in front of the anal fin, the so-called “pregnancy spot”. The female’s abdomen acquires a shape approaching a rectangular 2 to 3 days before the “birth”. The number of fry in a female of a certain species is determined by its size, age and living conditions. Fry immediately begin to feed on small crustaceans and escape from adult fish pursuing them. But first, they rise to the surface of the water to fill the swim bladder with air.
Most species of viviparous fish can be bred in the general aquarium, if the density of fish in it is small, and there are many small-leaved plants that serve as shelter. In this case, the most desirable plants are floating on the surface and in the water column. Cultivation succeeds better if any species is kept apart from others. The female shortly before “giving birth” should either be placed in a separate vessel with a large number of small-leaved plants located both at the bottom of the aquarium and on the surface of the water, or in an aquarium free from fish with one or more insulators arranged so that the falling fry can fall through the holes in the bottom, and then float. Naturally, the holes should be of such size that the females cannot swim through them.
Feeding up fry does not cause difficulties, as they eat almost any food of suitable sizes, but it is better to give them the young Artemia, small Cyclops and Daphnids. Fry grow very quickly and usually become sexually mature at 4-6 months. When breeding live-bearing tooth-like ones, selection of producers is of particular importance in order to continually improve their color and shape, and in the development of new breeds. hybridization.