Ecological mandarin fish breeding method based on natural breeding of bait fish

Abstract

The invention relates to an ecological mandarin fish breeding method based on natural breeding of bait fishes, and belongs to the technical field of aquaculture. According to the method, a crayfish culture pond or a river crab culture pond serves as an ecological mandarin fish culture pond, and aquatic plants with the coverage rate larger than 30% are planted. Propagation and growth characteristics of indigenous crucian carps are ingeniously utilized, the indigenous crucian carps are put from November of the previous year to January of the next year, and feed residues and excrement for breeding crayfishes or river crabs are used for providing food for the crucian carps; the aquatic plants provide inhabiting and molting places for the crayfishes or the river crabs, provide spawning places for the crucian carps, and purify water to form a stable ecological system. Large-size mandarin fish fries are put in the middle and last ten days of May in the next year, natural breeding of crucian carps provides continuous and palatable live bait fishes for mandarin fish, an efficient ecological circulation system is formed, and rapid growth of mandarin fish is promoted. The usage amount of the water quality improver and fishery medicine is zero, and mandarin fish, crayfish or river crab and crucian are harvested in autumn at the same time.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, specifically involving a method for efficiently and ecologically co-cultivating mandarin fish, crayfish, and crucian carp by utilizing the advantages of native crucian carp, such as their omnivorous diet, rapid gonadal development, long spawning cycle, and multiple spawning batches. Background Technology

[0002] Mandarin fish is a prized freshwater carnivorous fish with delicious flesh and high market demand. Because mandarin fish prefer live prey, traditional pond farming relies heavily on feeding them live prey fish (such as mud carp and silver carp). These prey fish require large-scale ponds (prey fish pond: mandarin fish pond = 4:1 to 5:1) for cultivation or are purchased externally, increasing farming and transportation costs. Furthermore, the supply is unstable, and purchased prey fish may carry pathogens, increasing the risk of disease in mandarin fish farming and requiring high labor intensity. Therefore, various polyculture and mixed-culture models have emerged in different ponds. Currently, the density of mandarin fish polyculture in crayfish or crab ponds is extremely low, generally not exceeding 10-15 fish / acre, making mass production impossible and resulting in low economic benefits. High-density polyculture models with over 100 fish / acre require artificial feeding of prey fish fry in the later stages of cultivation due to the growth of the prey fish and their unsuitable size. Native crucian carp are highly adaptable, omnivorous, have a strong natural reproductive capacity, early gonadal development, multiple spawning cycles, and a long spawning period. They have no natural predators in shrimp and crab ponds, making them highly susceptible to becoming dominant populations. This leads to competition with shrimp and crabs for food and oxygen, impacting shrimp and crab growth and yield, and increasing shrimp and crab farming costs. The conventional method is to use chemicals to kill native crucian carp, but this disrupts the aquatic ecosystem, poses a risk of drug residues, and disrupts the safety of aquatic products. Summary of the Invention

[0003] In order to achieve low-cost mass production of mandarin fish, with simple management and environmental protection, this invention provides an ecological farming method for mandarin fish based on the natural breeding of bait fish.

[0004] The ecological aquaculture method of mandarin fish of the present invention cleverly utilizes the reproductive and growth characteristics of native crucian carp. By releasing native crucian carp, they reproduce naturally, providing a continuous supply of palatable live bait fish for mandarin fish, forming an efficient ecological cycle system that promotes the rapid growth of mandarin fish.

[0005] The following are the operational steps for ecological aquaculture of mandarin fish based on the natural breeding of native crucian carp: (1) Management of native crucian carp release Native crucian carp are released into ponds that have been planted with aquatic plants between November of the previous year and January of the following year. The pond is a crayfish farming pond or a river crab farming pond; The coverage of aquatic plants in the pond is greater than 30%; The stocking density of the native crucian carp is 20-25 kg / mu, and the size is less than 60 grams / fish; Feed the crayfish or crabs according to their growth needs. The amount of feed should not include feeding native crucian carp. The crucian carp can feed on the leftover feed of the crayfish or crabs and other aquatic organisms. Until early March to early May of the following year, native crucian carp naturally reproduce in the aquatic plants of the pond, producing crucian carp fry. Shrimp and crab leftovers or aquatic organisms that reproduce rapidly in spring provide ample food for the crucian carp fry, thus achieving the natural cultivation of crucian carp fry. (2) Release of mandarin fish fry In mid-to-late May of the following year, mandarin fish fry were released into the pond, so that the crucian carp fry would serve as the main live food for the mandarin fish. The stocking density of the mandarin fish fry is 120-150 fish / mu, with a size of 7-9 cm; (3) Aquaculture management Feed the crayfish or crabs with formulated feed according to their growth needs, without feeding them any special bait fish or formulated feed for mandarin fish; harvest the mandarin fish, crayfish or crabs and crucian carp simultaneously in autumn.

[0006] Further technical solutions are as follows: In step (3), the oxygenation equipment is turned on in the morning and evening during the hot summer season to keep the dissolved oxygen in the water above 6.0 mg / L.

[0007] The oxygenation equipment is a waterwheel aerator or a microporous aerator, with a power of 1.0-1.5 kW / mu. The beneficial technical effects of this invention are reflected in the following aspects:

[0008] (1) Low cost and high output Utilizing the strong reproductive capacity of native crucian carp, a large number of crucian carp fry are naturally propagated in the pond. Leftover feed and excrement from farmed crayfish or crabs provide food for the fry, achieving natural cultivation. Aquatic plants provide habitat and molting grounds for crayfish or crabs, and spawning grounds for crucian carp, while also purifying the water, forming a stable ecosystem. This eliminates the huge costs of purchasing or specially cultivating bait fish, bringing the feed and labor costs of mandarin fish farming close to zero. High-density polyculture of mandarin fish can be achieved, resulting in mass production; simultaneously, high-quality mandarin fish, crayfish or crabs, and crucian carp are harvested, with profits per acre far exceeding those of single-species farming, and strong resilience against market risks.

[0009] (2) High matching degree between bait and fish By precisely controlling the number of native crucian carp, the stocking time, and the size of mandarin fish fry—that is, stocking 20-25 kg of native crucian carp per mu from November to January of the following year, and stocking large-sized mandarin fish fry in May—the density of palatable crucian carp fry is highly matched with the feeding needs of mandarin fish, and the size of the bait fish is always matched with the feeding mouth size of mandarin fish, resulting in high utilization of bait fish and fast growth rate of mandarin fish.

[0010] (3) Ecological cycle, quality improvement Mandarin fish eliminates crucian carp fry in the pond, reducing competition with the main farmed species, crayfish or crabs, which is beneficial to the growth of the farmed crayfish or crabs. At the same time, the use of water quality improvers and veterinary drugs is zero, ensuring the quality and safety of the pond's aquatic products. The farming process eliminates the need for complex feed fish fry cultivation and management; the main management work focuses on water quality and oxygenation, greatly reducing labor intensity and technical barriers. Detailed Implementation

[0011] The present invention will be further described in detail below with reference to the embodiments. Example 1

[0012] The following are the operational steps for the ecological farming of mandarin fish based on the natural reproduction of bait fish: (1) Management of native crucian carp release In 2024, a crayfish farming pond with an area of ​​approximately 1.8 mu (about 0.13 hectares) was selected in Feixi County, Anhui Province, with a surrounding embankment about 1 meter high. Before the winter of the previous year, the pond was cleaned and dried, and aquatic plants such as *Hydrilla verticillata* were planted, achieving a plant coverage rate of 35%. The pond rental cost was 1200 yuan.

[0013] On December 22, 2024, 22 kilograms of native crucian carp were released, with the largest individual weighing no more than 60 grams. The fish came from the surrounding rice-shrimp farming fields, costing approximately 120 yuan.

[0014] Routine Management: Starting in early February of the following year, maintain the water level at around 50 cm to encourage crayfish larvae to emerge from their burrows and feed. Feed them with formulated crayfish feed once a day in the evening, approximately 2-3 jin (1-1.5 catties) per day. Later, the amount of feed should not exceed 10% of the total weight of the crayfish (crabs) in the pond. Do not feed them native crucian carp; allow them to grow naturally. From March to early May of the following year, the native crucian carp will naturally reproduce among the aquatic plants in the pond, producing crucian carp larvae.

[0015] (2) Release of mandarin fish fry On May 20, 2025, at a water temperature of 23℃, 300 healthy mandarin fish fry, each measuring 7-9 cm, were released into the pond at a cost of approximately 750 yuan. The large number of naturally bred crucian carp fry provided ample and palatable live food for the mandarin fish.

[0016] (3) Aquaculture management Throughout the summer, in accordance with the crayfish's growth needs, apart from feeding them crayfish feed (total feed cost approximately 500 yuan), no additional mandarin fish bait or formulated feed was provided. A 1.5 kW waterwheel-type aerator was installed in the pond and operated for 2 hours each at night and in the early morning to ensure sufficient dissolved oxygen (electricity cost approximately 500 yuan).

[0017] On September 28, 2025, the pond was drained for harvesting. The total harvest included: approximately 300 jin of marketable mandarin fish with an average size of 1.3 jin / fish; 180 jin of marketable crayfish; and 50 jin of large native crucian carp weighing over 150 grams / fish.

[0018] Profit Calculation: 300 jin of mandarin fish × 35 yuan / jin = 10,500 yuan; 180 jin of crayfish × 9 yuan / jin = 1,620 yuan; 50 jin of crucian carp × 15 yuan / jin = 750 yuan; Total expenditure is about 3,500 yuan, total income is 12,870 yuan, total profit is 9,370 yuan, and profit per mu is 5,305 yuan, which shows significant economic benefits. Example 2

[0019] The following are the operational steps for the ecological farming of mandarin fish based on the natural reproduction of bait fish: (1) Management of native crucian carp release In 2024, a crab farming pond with an area of ​​approximately 5 mu (about 0.33 hectares) and a depth of 2.0 meters was selected in Lujiang County, Anhui Province. Before the winter of 2024, the pond was cleaned and dried, and aquatic plants such as *Hydrilla verticillata* were planted, achieving a coverage rate of 40%. The pond rental cost was 2500 yuan.

[0020] On January 8, 2025, 125 kg of native crucian carp were released, with the largest individual weighing no more than 50 grams. The fish came from the surrounding rice-shrimp farming fields, and the cost was about 190 yuan.

[0021] Routine Management: In March of the following year, maintain the water level at approximately 80 cm and stock with 600 crab larvae, each weighing 50 crabs per kilogram (cost 420 yuan). Feed the crabs with formulated feed once daily, based on their activity level, at a rate of 6% of their total weight. Gradually increase the feeding amount as the water temperature rises, feeding twice daily, once in the morning and once in the evening, but never exceeding 10% of the total weight of the crabs. Do not feed native crucian carp; allow them to grow naturally. From March to early May of the following year, the native crucian carp will naturally reproduce among the pond's aquatic plants, producing larvae.

[0022] (2) Release of mandarin fish fry On May 26, 2025, at a water temperature of 24℃, 700 healthy mandarin fish fry (7-9 cm in length) were released into the pond, costing approximately 1750 yuan. Crucian carp fry served as the primary live food for the mandarin fish.

[0023] (3) Aquaculture management Throughout the summer, in accordance with the growth needs of the river crabs, apart from feeding them river crab feed (total feed cost approximately 1620 yuan), no additional mandarin fish bait or formulated feed was provided. A 1.0 kW microporous aeration device was installed in the pond and turned on for 2 hours each at night and in the early morning to ensure sufficient dissolved oxygen (electricity cost approximately 1800 yuan).

[0024] On October 20, 2025, the pond was drained for harvesting. The total harvest was: approximately 756 jin of marketable mandarin fish with an average size of 1.2 jin / fish; 216 jin of marketable river crabs; and 108 jin of large native crucian carp weighing over 150 grams / fish.

[0025] Profit Calculation: 756 jin of mandarin fish × 35 yuan / jin = 26460 yuan; 216 jin of river crab × 45 yuan / jin = 9720 yuan; 108 jin of crucian carp × 12 yuan / jin = 1296 yuan; Total expenditure is about 6530 yuan, total income is 12870 yuan, and profit reaches 30946 yuan. The profit per mu is 6189.2 yuan, which shows very significant economic benefits.

[0026] Those skilled in the art will readily understand that the above embodiments 1-2 are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for ecological aquaculture of mandarin fish based on the natural breeding of native crucian carp, characterized in that, The operation steps are as follows: (1) Management of native crucian carp release Native crucian carp are released into ponds that have been planted with aquatic plants between November of the previous year and January of the following year. The pond is a crayfish farming pond or a river crab farming pond without a ring ditch. The coverage of aquatic plants in the pond is greater than 30%; The stocking density of the native crucian carp is 20-25 kg / mu, and the size is less than 60 grams / fish; Feed the crayfish or crabs according to their growth needs. The amount of feed should not include feeding native crucian carp. The crucian carp can feed on the leftover feed of the crayfish or crabs and other aquatic organisms. It wasn't until early March to early May of the following year that the native crucian carp naturally reproduced among the aquatic plants in the pond, producing crucian carp fry. (2) Release of mandarin fish fry In mid-to-late May of the following year, mandarin fish fry were released into the pond, so that the crucian carp fry would serve as the main live food for the mandarin fish. The stocking density of the mandarin fish fry is 120-150 fish / mu, with a size of 7-9 cm; (3) Aquaculture management Feed the crayfish or crabs with formulated feed according to their growth needs, without feeding them any special bait fish or formulated feed for mandarin fish; harvest the mandarin fish, crayfish or crabs and crucian carp simultaneously in autumn.

2. The method for ecological aquaculture of mandarin fish based on the natural rearing of native crucian carp according to claim 1, characterized in that: In step (3), the oxygenation equipment is turned on in the morning and evening during the hot summer season to keep the dissolved oxygen in the water above 6.0 mg / L.

3. The method for ecological aquaculture of mandarin fish based on the natural breeding of native crucian carp according to claim 2, characterized in that: The oxygenation equipment is a waterwheel aerator or a microporous aerator, with a power of 1.0-1.5 kW / mu.