CATDOLL : CATDOLL: How many ways do fish lay eggs? What are the reproductive characteristics of fish?

1. How many ways do fish lay eggs?

There are three types of fish reproduction: oviparous, ovoviviparous and viviparous.

1. Oviparity is the reproductive method of most fish. Fish lay eggs outside the body, and the embryonic development takes place outside the body. The embryonic development process completely relies on the nutrients in the eggs.

2. Ovoviviparous fertilized eggs develop in the female reproductive tract, mainly relying on yolk nutrition during development, and have no nutritional relationship with the mother, or the mother's reproductive tract mainly provides water and minerals, and finally the mother produces fry. Such as guppies.

3. The embryos of some viviparous elasmobranch fish are connected to the mother through blood circulation. The nutrients needed for embryonic development are not only provided by the yolk of the embryo itself, but also by the mother. There are some protrusions on the wall of the oviduct where the embryo develops, which are connected to the embryo, forming a structure similar to the placenta. The mother sends nutrients to the embryo through this structure. For example, the gray star shark.

2. What are the reproductive characteristics of fish?

Most fish are dioecious, and chase, lay eggs, ejaculate, and hatch when they reach sexual maturity. The feeding habits of fry are different from those of adult fish, and gradually become the same as they grow up. Some fish are fertilized and develop in vivo, and female fish give birth to small fish directly, which is ovoviviparous or pseudoviviparous.

The eggs of some cartilaginous fish and a few bony fish are not only fertilized in vivo, but also develop in the oviduct or ovarian cavity. The embryos are well protected by the mother, and the reproduction of these fish is generally not restricted to a specific breeding site. The oviparous female must expel the eggs from the mother's body, and they can only meet the sperm expelled by the male in the water to complete fertilization and embryonic development.

3. What is the concept of fish breeding cycle?

Ordinary fish can ovulate in spring when the water temperature reaches above 20 degrees. However, different fish have different breeding times. For example, carp spawns from March to August, with the peak period from April to June. Grass carp spawns from early May to early June, with the peak period in mid-to-late May.

4. How do fish reproduce through sowing?

After the fish chases its tail, it will generally lay eggs in three or four days. Usually during the breeding season, male and female fish will mate, and after successful pairing, they will chase each other. This is the fish trying to mate, so after a few days, the female fish will lay eggs, and the male fish will fertilize them. After obtaining the fertilized eggs, the parent fish are usually removed from the tank to prevent them from accidentally eating the eggs and affecting the hatching of the fry.

5. What are the signs before fish spawn?

Before fish spawn, the signs vary for different fish.

Mainly, the color of the male fish will become brighter than that of the female fish (nuptial color). When the female fish reaches sexual maturity, her abdomen will be more swollen, and the male fish will constantly chase the female fish.

The reproduction method of oviparous fish is: the male and female broodstock ovulate and fertilize at the same time, and the eggs are fertilized in the water. The vast majority of fish reproduce from oviparous offspring, but due to different species, their maturity, mating, spawning process, egg characteristics, etc. are also different. Even for the same fish, the maturity period varies greatly between different genera and species. Generally, small fish can mature in a few months and can reproduce once in 2-3 weeks or a few weeks; while large fish can mature in several years or more than ten years and reproduce once a year. For female fish to lay floating eggs, male fish will first spit foam to make a nest. Some male fish will gather grass to make a nest, and the fertilized eggs will hatch in the floating nest. Some fish eggs need to hatch in the starting drift of the water flow. For female fish to lay sticky eggs, the fertilized eggs need to adhere to water plants or other objects to hatch. The fertilized eggs of sinking eggs sink into the gaps between gravel to hatch. The spawning process and the time when fertilized eggs hatch fry also vary from species to species. Water temperature, light, water quality, dissolved oxygen content, etc. will also affect the hatching of fertilized eggs. If there are any deficiencies, the incubation period will be prolonged, the hatching rate will be reduced, and even deformed seedlings will be produced. Therefore, when artificially breeding these fish, it is necessary to understand their reproductive characteristics in advance and operate carefully. Female oviparous fish may carry a large number of eggs and lay a large number of eggs, but the number of fry obtained may be small, and some may even be far less than the number of eggs laid. Due to various reasons, the eggs laid by female fish are affected in three aspects: fertilization, hatching and survival of fry.

6. In what season do fish begin to spawn?

Fish usually spawn from March to May, with the largest number of eggs laid in late spring and early summer. There are some differences due to temperature differences. The temperature in the northern region is lower, so the ovulation time is later. The condition for spawning is that the water temperature reaches above 14 degrees Celsius, preferably 18-25 degrees Celsius.

Oviparous reproduction: refers to the reproduction of fish through external fertilization. When the fish reaches sexual maturity, the female fish releases eggs and the male fish releases sperm. When the eggs and sperm meet and combine in the water, the fertilization process is completed. After a period of time, these fertilized eggs will slowly develop and become small fish.

7. How do spawning fish reproduce?

Different types of fish have different ways of laying eggs. There are three types of fish reproduction: oviparous, ovoviviparous and viviparous.

1. Oviparous reproduction: refers to the reproduction of fish through external fertilization. When the fish reaches sexual maturity, the female fish will expel eggs from the body, and the male fish will expel sperm from the body. When the eggs and sperm meet and combine in the water, the fertilization process is completed. After a period of time, these fertilized eggs will slowly develop and become small fish.

2. Ovoviviparity: The fertilized egg develops in the female reproductive tract, relying mainly on yolk nutrition during development and has no nutritional relationship with the mother, or the maternal reproductive tract mainly provides only water and minerals, and the mother eventually gives birth to the fry.

3. Viviparity refers to the development of fertilized eggs in the mother's body, and the mother provides the nutrients needed for fetal development. After a period of development and growth, the fetus is produced from the mother's body. Extended information: Fish spawning is roughly in spring and summer. 1. The breeding period of crucian carp is from March to July, and April is the peak breeding period. In the southern region, generally after mid-March, when the water temperature rises to about 17°C, crucian carp begins to spawn, and the breeding activity is most prosperous when the water temperature rises to 20-24°C. Rainfall, micro-flowing water and sultry climate can induce spawning for crucian carp in the breeding period. 2. The spawning season of carp varies from region to region. It can spawn from March to August, and the peak period is from April to June. 3. The reproductive season of grass carp is from early May to early June, and the peak period is mid-to-late May. 4. The breeding season of silver carp is from mid-April to July, and from May to June.

8. Briefly describe the water ecological factors that affect the overwintering survival of fish?

1. Poor physical condition of fish during the winter: Generally speaking, large-sized fish have good physical condition and high survival rate during the winter. Small-sized fish have poor physical condition and less nutrients such as fat accumulated in their bodies. It is difficult for them to maintain energy for survival during the long wintering period and they often die due to physical weakness. However, if the feed formula is unreasonable, the vitamin content is unbalanced or the amount of growth promoter added exceeds the standard, although it does not affect the growth of the species, it will seriously affect the physical condition of the fish and make the fish "fat". The immunity of such fish decreases and it is difficult to survive the winter. Especially in the late winter, they are susceptible to infection by pathogens, fish diseases break out, and wintering losses occur.

2. Hypoxia and low temperature in subglacial water:

(1) Snow is not cleared in time or the clearing area is too small, resulting in poor light transmittance, which affects the photosynthesis and oxygen production of phytoplankton.

(2) The water is thin and lacks fertilizer, the amount of phytoplankton is small, and the oxygen production is insufficient; the zooplankton reproduces in large numbers, and the oxygen carrying capacity increases.

(3) The bottom mud of old ponds is too thick and the high organic matter content causes hypoxia.

(4) Improper water injection or oxygenation. Blindly flushing water or adding oxygen for a long time will cause the water temperature in the pond to drop rapidly, and the turtles will be frozen to death.

3. Harmful substances exist in the wintering pool: Due to the increase in wintering density, harmful gases cannot escape after ice closure, and accumulate more and more in the water. Once the standard is exceeded for a long time, it will cause harm to the wintering fish. The most easily produced chemicals are ammonia nitrogen, nitrite, hydrogen sulfide and carbon dioxide.

4. Fish overwinter with diseases: Pathogens infected during the summer and autumn breeding stage are not treated in time, and the disease accumulates in the winter. The five species have poor physical fitness and poor ability to resist diseases and adverse environments, which increases the chance of infection with fish diseases and leads to fish disease outbreaks.

9. Fish that reproduce asexually?

Asexual species such as the Amazon sailfin perch generally use gynogenesis to reproduce, and all offspring are "clones" of their mother. In order to develop embryos, female Amazon sailfin perch will mate with males of similar species, but they do not use the male's sperm, so in theory the offspring will not inherit any genes from the father.

Scientists believe that if sexual species reproduce asexually, they will develop genetic defects and eventually become extinct after a few generations, so the Amazon sailfin perch should have become extinct long ago.

According to mathematical models established by scientists, this asexual female fish should have become extinct 70,000 years ago, but today they still reproduce in southeastern Texas and northeastern Mexico.

What allows the Amazon sailfin perch to survive? Researchers at the School of Biological Sciences at the University of Edinburgh in the UK believe that it is a genetic "trick" that helps the Amazon sailfin perch survive. They may have obtained some DNA from male fish of other species to trigger reproduction and update their own gene pool.

Dr. Lawrence Levy said the study of the Amazonian sailfin perch may also help better understand the survival secrets of other species that reproduce in a similar way. One of them is the salamander, which has been thriving on Earth for more than a million years.

10. How do fish reproduce?

Evolution means having many children, each with slight differences (mutations), and then those that adapt to the environment survive, reproduce, and pass on their genomes.

In the example of the fish biting the hook, the fish that are curious and less vigilant are selected and killed. In this way, the less curious and more vigilant fish are more likely to survive and give birth to offspring. The proportion of fish that are not easily caught will increase in the next generation.

If fishermen kill enough individuals, selection may be complete within a single generation!

In fact, because there are no restrictions on personal recreational fishing, many non-migratory fish in China's coastal waters have evolved and become more cautious in the past 10 to 20 years. Everyone feels that it is becoming increasingly difficult to catch fish.

Similarly, in North America, fishing has never been very difficult because of the restrictions on the amount of fish caught by sports fishing licenses. Fish that are wary or curious about the food that is brought to their mouths have the opportunity to reproduce, and both genes will be passed on to the next generation. Intuitively speaking, fish are more "stupid".

But of course these fish that don't bite the hook don't "know", they are just more picky and more easily frightened. As for understanding the meaning of "fishing line" and "trap", they need to evolve consciousness first, and that may never happen.

peace out.