Feed Feeding Amount Control, Density and Artificial Breeding Techniques for Carp Farming
The freshwater fish species carp, also known as li guaizi, li zi, mao zi, and red fish. Originally from Asia, later introduced to Europe, North America and other regions, omnivorous.So what feed is generally used for farming carp, and how is the feeding amount controlled? What is the farming density? What are the artificial breeding techniques?
What feed is generally used for farming carp, and how is the feeding amount controlled?
The feed formulas carp loves most:
1. Wheat bran 45%, soybean cake 40%, barley 10%, fishmeal 5%, with appropriate amounts of multivitamins, inorganic salts, lysine and methionine added, feed coefficient 2.
2. Wheat bran 45%, fishmeal 30%, soybean cake 15%, barley 10%, with the same additives as (1), feed coefficient 2.
3. Soybean cake 50%, fishmeal 15%, wheat bran 15%, rice bran 15%, multivitamins 1%, inorganic salts and antibiotic by-products 1% each, binder 2%, feed coefficient 2.7.
4. According to actual conditions, scientific selection and scientific feeding are what bring higher farming benefits. At present, the mainstream farming model is large-scale mixed polyculture with rotational harvesting and restocking, and farmers find it difficult to accurately estimate the weight of fish in their ponds. Controlling the feeding rate according to how the farmed species feed can easily lead to an excessively high feeding rate.
Under such management measures, within a certain period the farmed species grow too fast, causing a decline in the fish body's immunity, and various fish diseases follow one after another. On the one hand this causes feed waste, leads to deterioration of water quality and raises farming costs; in serious cases it may result in a total loss.
What is the farming density for carp?
Generally speaking, it is best to farm about 3000 jin of carp per mu of pond, together with about 300 jin of other fish species. Stocking too many easily leads to disease outbreaks and sharply increases farming costs. Generally speaking, black carp, grass carp, silver carp and bighead carp are all polycultured! Looking at Henan now, the farming density of the four major Chinese carps has reached as high as ten thousand jin! Generally speaking, a 1-mu pond polycultured to 2000-3000 jin! Of course, differences in region, climate, environment, water quality and farming techniques and inputs also create very large gaps!
What are the artificial breeding techniques for farming carp?
1. Daily feeding methods
The size of the fish pond is unlimited, and the water depth should preferably be 1.2-1.5 m. However, the feed coefficient in large ponds will be somewhat higher. Carp fry of different sizes can also be put in in stages and batches to facilitate rotational harvesting and restocking. For daily management, carry out the “three patrols and four checks” in the morning, at noon and in the evening, to keep track of the climate, fish condition and disease situation, and keep the fish growing quickly. At the same time, water should be added regularly, and flood prevention and escape prevention work should be done well.
In addition to following the eight-character guideline of “water, seed, feed, density, mixing, rotation, prevention, management”, feeding should also meet standards such as “superior seed, fine feed, good water, fine management”. Feeding should adhere to the “four fixeds” principle of fixed quality, fixed time, fixed location and fixed quantity, and feeding should be carried out according to the feeding rhythm of the fish species. Carp like to live in the lower layer of the water body. The optimum growth water temperature is 25°C-32°C. Above 32°C or below 15°C, growth slows markedly, and below 10°C feeding stops. The suitable dissolved oxygen level is above 4.5 mg per liter; below 2 mg they eat less, and at 1 mg they stop feeding and gasp at the surface. Vigorously grasp the feeding of fish fry during the peak feeding period in the early stage, especially from the inch-size stage to within 25-30 days, because growth is especially fast during this period, with both body length and body weight increasing quickly. Some farmers have a feeding rate of more than 10% during this period. The earlier the fry open their mouths, the earlier the growth starting point and the better the growth. They should transition smoothly to feeding with complete compound feed as early as possible, and it is required to mainly use compound feed, with crude protein above 30%, feeding 4-6 times a day, at a feeding rate of 3%-8%.
2. Broodstock cultivation and seed selection
Broodstock cultivation ponds of 1-2 mu, with a water depth of about 1.2 m, sheltered from the wind and facing the sun, with convenient water inlet and drainage. Disinfect with quicklime or bleaching powder before stocking. Stock 150-200 kg per mu. During artificial propagation, males and females should be separated to prevent them from mating and spawning on their own. Carp generally reach sexual maturity at age two, and some individuals can also mature at age one. The spawning season varies with region, and they can spawn in batches. Spawning can occur from March to August, with April to June being the peak period. Spawning grounds are mostly in shallow lake bays or river bends with dense aquatic vegetation. The eggs are strongly adhesive, and after spawning they firmly adhere to the aquatic plants. The number of eggs carried varies with age and individual size, ranging from 150,000 to 800,000. After the eggs are laid, at a water temperature of 15°C-20°C, fry can hatch in 4-6 days.
Carp that are maturing sexually for the first time or are in the aging period have poorer egg-carrying capacity and egg quality and are not suitable as broodstock. Adult fish with a good body shape, a body length to body height ratio of 3:1, strong activity and no injuries can be selected as broodstock. It is best if the female fish is at least 2 winters old and weighs 1.5 kg, and the male fish is 2 winters old and above 1 kg. In the non-reproductive season, the female fish has a wide body, a high back, a small head, a relatively large and soft abdomen, small round and wide pectoral and pelvic fins, and a flat or slightly protruding cloaca with radiating folds; the male fish has a narrow and long body, a relatively large head, a small and hard abdomen, large and pointed long pectoral and pelvic fins, and a slightly inward-sunken anus with no parallel folds. In the reproductive season, the female fish's abdomen is soft and round-sac-shaped, and the anus and genital pore are relatively large, slightly red and protruding; the male fish's abdomen is relatively small, the gill cover, pectoral and pelvic fins have obvious secondary sexual characteristics, the anus and genital pore are sunken and not red or swollen, and lightly pressing the abdomen causes milky white semen to flow out.
3. Spawning and breeding management
Induced spawning is divided into two methods: natural spawning and artificial induced spawning. Carp generally spawn from 22:00 on the same day to 9:00 the next morning, lasting 2-3 days. 30-35 groups of well-matured brood carp can be placed in the same pond at a female-to-male ratio of 1:1-1.5, and fresh water slowly added. 1-8 thin iron wires are stretched across the water surface, and artificial spawning nests are hung on the wires (or bamboo split in two with the nest clamped in the middle and placed on the water surface). Usually each group of brood fish should be provided with 4-6 spawning nests. Check and clean the spawning nests every afternoon, move the nests with eggs attached into the hatching pond, and at the same time replenish new spawning nests. If spawning is poor after placing them together, the water level can be lowered to let the sunlight shine on them, more vitamin E can be added to the feed, or a slight flow of water can be used as stimulation. To ensure the uniformity of the fry, eggs from the same day should be put into incubation together, which can also prevent the number of dead eggs from increasing due to eggs sticking together into clumps.
Artificial induced spawning is mostly seen in fish seed farms. For each kg of female fish, use 600-1000 ml of artificial chorionic gonadotropin or 30-50 micrograms of luteinizing hormone-releasing hormone analogue, or use them mixed at reduced doses, with the dose for male fish halved. Generally, at 18:00 on a clear afternoon, inject the predetermined dose once into the thoracic cavity at the base of the pectoral fin, then immediately move them into the spawning pond, and add fresh water for half an hour. At a water temperature of 18°C and after lasting 6-15 hours, they will become sexually excited and spawn. Note that the higher the water temperature, the shorter the response time, and vice versa.
After induced spawning, the brood fish can spawn on their own in the pond, by the same method as the natural spawning type. If artificial egg collection is used, the fish can be scooped up before the peak of sexual excitement, the water on the fish body wiped off with a towel, the eggs squeezed into a dry porcelain basin, and semen quickly squeezed in, stirred with a feather to allow full fertilization, and then the fertilized eggs evenly spread on the spawning nests and placed in the hatching pond for incubation. Alternatively, after de-adhesion with a talc solution, flowing water incubation can be used, and at a water temperature of 16°C-22°C, fry can emerge in 3-5 days.
For natural incubation, put 300,000-500,000 fertilized eggs per mu of pond, and eggs from the same day should be put in together to ensure uniform fry specifications. Special attention should be paid to preventing saprolegniasis, and the spawning nests with eggs attached can be pre-soaked and washed with 0.3‰ formalin or malachite green.
For de-adhesion incubation, the water flow rate should be adjusted in good time, to the degree that the fish eggs do not sink but remain suspended in the water, and at the same time screen window clogging should be prevented. When fry hatch, slightly reduce the flow rate to prevent the current from being too rapid and consuming the fry's energy.
Sudden weather changes during the spawning period, poor water quality, low dissolved oxygen, and fish eggs being parasitized by mold can all affect the hatching rate. Measures should be found to prevent their harm, increase the hatching rate and ensure farming benefits.
4. Strengthen disease prevention
Furunculosis is mostly seen in polyculture fish ponds dominated by silver carp and bighead carp. It has no typical disease season and can occur year-round. The back skin and muscle tissue of diseased fish become inflamed, then ulcerate into purulent sores, which feel swollen to the touch. The area around the purulent sores is inflamed and congested, the fin rays rot into a brush shape (also called broom fins), and in severe cases the intestinal tract bleeds and becomes inflamed. Fish species, water bodies and ponds should be thoroughly disinfected; make medicated feed with 80 mg of ciprofloxacin per kg of feed for oral administration, and use 1 international unit of bleaching powder per mu to disinfect the water body, for 3 consecutive days.
In scale protrusion disease, the body surface of diseased fish is rough, and some scales (mostly on the rear part of the fish body) open outward like a pine cone, hence the name pine cone disease; the scale sacs accumulate translucent or blood-containing exudate, causing the scales to stand up, hence it is also called erect scale disease. If slight pressure is applied to the scales with a finger, the exudate spurts out from under the scales, and the scales fall off accordingly. Red ulcers form where the scales have fallen off, the eyeballs protrude, and the abdomen swells, with death after 2-3 days. This disease has 2 epidemic periods, one being the carp spawning period and the other the carp overwintering period, with a mortality rate of 45%, and up to 85% at the highest. Care should be taken when seining to prevent the fish from being injured. The fish body, water quality and pond should be disinfected. 50-80 mg of oxytetracycline or chlortetracycline can be added per kg of feed to make medicated bait for feeding.
Carp philometriosis, also known as red fine nematode disease, mostly harms adult carp. In winter the parasite lives under the scales, but the parasite is small and does not show disease; when the water temperature warms in spring, the parasite grows faster and causes disease in the fish. The scales of diseased fish are loose, and the muscles around the scales are congested, inflamed and ulcerated, easily causing concurrent saprolegniasis. Under the scales where the parasite lives, red-purple irregular patterns appear, and lifting the scales reveals the red parasite. Quicklime can be used for strict disinfection to kill the larvae. Wipe the affected area with iodine wine or 1% potassium permanganate, or soak and wash with 2% salt water for 10-20 minutes.