Ovarian development ahead of schedule! Is it environmental stimuli such as light, temperature, and running water, or is there a problem with fish species, drugs, nutrition, density, etc.?
Text/Figure Aquatic Frontier Lin Zhenwu
astound! Recently, some Farmers in Foshan have reported that their two ponds of raw fish just farmed this year are now only 2 or 2, and they have actually grown finger-sized fish eggs! According to the owner of the fish pond: "These two ponds of fish are about the orthogonal splash of April, in May more than 200 pounds of pond, the small pond 5 acres put 30,000 seedlings, the big pond 8 acres put 60,000 seedlings, originally planned to catch a few fish to go to the pharmacy for routine testing, but unexpectedly found that the fish precocious, 2 of the 4 fish appeared fish eggs, the fish pond owner directly called himself to raise fish for so long has not encountered, very surprised! ”
"Fish Eggs"
In the communication with the author, the farmer said that he was also confused and surprised by this situation. "My fish pond had a raw fish Schubert aeromonas infection some time ago, and I used some antibiotics to treat it, will it have anything to do with this?" Or is it related to the feed you eat? Farmers said. It is understood that there is no feedback from the owner of the pond in other people's ponds near the farmer, and the farmer friends who raise the same batch of splashes have not said that there is a similar situation of the same species. Pond owners are worried that "fish spring" will affect the growth rate of fish, resulting in problems such as high material ratio.
The author has communicated with some people in the industry, and the following are the views of some friends in the industry:
"Normal, it will soon disperse on its own, and you can dissect it again after a month."
"Fish eggs also appeared in grass carp in those years, and blue fish in 2 years also encountered them."
"The first time I met, would it be left behind by the unclean pond before?" Fish a few more and see."
"It may be related to the density or temperature of the culture, resulting in abnormal growth hormone secretion and premature ovarian maturation."
"During this time, the problem of raw fish Schubert is more obvious, will it be related to too much antibiotic feeding?"
"This phenomenon occurs every year, but no one has noticed it before, but it does affect the speed of raw fish and the absorption and utilization of feed."
"This is very strange, normal should not have such a large gonad, wild blackfish are very small and can produce seeds, will it be the wild species ran in the previous year?"
It is understood that hybrid snakehead is an important aquaculture object that has risen in the south of China in recent years, it has the advantages of tender meat, delicious taste, high nutritional value, fast growth rate, strong living ability, few diseases, low mortality, easy transportation of live fish and other advantages and is welcomed by farmers, the current total output of blackfish aquaculture in the country exceeds 500,000 tons. The sexual maturity time of the snakehead varies according to the living area, in the south, the snakehead is mature at the age of winter, the middle and lower reaches of the Yangtze River are mature in the second winter, and the ovarian maturity coefficient is lower from August to March of the following year, rising from March to April of the following year, and maintaining a high level from May to August, so May to August of each year is its breeding season. Studies have shown that the minimum sexually mature fish that snakeheads can spawn is about 35 cm long and weighs about 400 g.
When the author consulted the data, he found that there was a preliminary study on the reasons for the early sexual maturity of blackfish cultured in greenhouse cement ponds, which mentioned the causes of precocious puberty, which roughly had three aspects: First, long-term intake of high-protein, high-fat bait, so that the body length, weight rapid growth, while accelerating the development of gonads. Because the bait provides a large number of nutrients required for the development of germ cells, the number of germ cells increases rapidly, the volume increases rapidly, so the reproductive glands develop early; the second aspect, the difference in light and temperature and the natural state is also the main factor causing precocious puberty, the light intensity is high, the water temperature has also been maintained at a high level, stimulating the development of the gonads; the third aspect, the frequent replacement of fresh water will also stimulate the development of the gonads, through neuromodulation to accelerate the maturity of the gonads.
Relevant literature shows that the gonadal development of blackfish is closely related to body length, weight and nutrition, and environmental conditions, but not closely related to age. As for why the fish pond mentioned in this article appears in this situation, there is no conclusion at present, in the past two days, the pond owner has fished several dissections but has not found that there is, the overall proportion of fish with early development of gonads should not be too high, but this phenomenon will have a certain impact on the growth and development of fish, or we must pay close attention to it, eliminate precipitating factors, and improve the efficiency of breeding.
For raw fish gonadal development, what do you think is causing it? Comments are welcome in the comment area.
【Keywords】: Raw fish precocious aquaculture