The excellent cultured species are expected by farmers. It not only brings good economic benefits to farmers, but also provides people with high-quality and delicious animal protein. Over the past ten years, relevant aquaculture units have introduced new breeds of aquaculture from Australia, some of which have achieved phased results, such as the well-known Scortum barcoo, and some are still in the incubation stage. Some farming effects are not very good. From late April to early May 2002, the author visited the Euroa Town in Victoria Province at the invitation of Australian Aquaculture Co., Ltd. to inspect the company's main gems and insects.
When we arrived in Euroa, we were greeted by lush meadows, trees, flowers, Bay Pond and rivers. It was a garden-style recreational fishing destination. The Australian Aquaculture Company is a prestigious company in the town. When we talked to the locals, we were well known when we talked about gems and worms. If friends from afar can taste worms, the hospitality specification is higher.
Australia is a sparsely populated developed country. Freshwater aquaculture is mainly distributed in the southeastern provinces of Victoria and New South Wales and in the north-central province of Queensland. It is now known as Australia’s National Treasure – a brief introduction to the worms. For reference by domestic farmers.
1 The taxonomic status of the maggots, Australia, or Macculochella peeli, is Percichthyidae. The Pechichthyidae is also translated into the genus Ophiopogon or the genus Asperidae. ). • Amaranthidae is a species of freshwater fish distributed in Australia and South America (mainly Argentina and Chile). The old classification system placed it in the department, which is now independent. The current custom at home and abroad is known as Murray, derived from the original habitat - Murrayriv-er in southeastern Australia. It is also known for its yellow-brown mottled spots on the body surface. Spots, orthodox maggots should be worms.
2 The economical character of the worms is the largest freshwater fish in Australia so far, and it is also the largest in the world. In the literature, a 1.8-meter-long, 113.5-kg worm beetle was captured in a river near Walgett in 1902. In Australian rivers, gamers caught 20-40 kg of individuals. 2-3kg individuals abound. Since 1990, the Fisheries Research Institute has carried out research on artificial breeding of earthworms in order to restore fish resources that have been degraded due to the influence of water conservancy facilities and environmental pollution. At present, it has been able to hatch in an artificially controlled environment. Some of the seedlings are released in natural waters. Some of the seedlings are used as seedlings for artificial breeding, and some of the seedlings are exported to foreign countries. The moth-eaten quail meat is white, delicate and strong, with few intermuscular thorns. It does not have the smell of common fish and has a special aroma. According to the determination of fresh fish, the fish contains four kinds of aroma amino acids and contains certain Quantity of EPA and DHA. During the cooking process, it is easily peeled and easy to puncture. It is often eaten in the form of worms, worms, or fish in Australia and its neighboring countries and regions. Larvae also export to Hong Kong, Macao and Taiwan and Southeast Asia. Its price is $20/kg in Melbourne.
3 The main characteristics of the worm beetles The fish is spindle-shaped with a slightly bulging back of the head. The length of the head is 1/3 of the full-length, mouth-end position, and splitting of the mouth. The naked eye appears to have no scales, and it is smooth with hands. The actual body is covered with small, dense scales. On both sides of the body, there are worm-like patterns. The back of the body is yellow-black on the sides, and the abdomen is yellowish-white in color. The body shape and body color are extremely beautiful. The back has 11 hard spines, more than 13 (14) pieces, 19 pectoral fin rays, 1 hard pelvic fin, 5 pieces, 3 anal fins, 13 fins. At the end of the tail, the shape resembles a truncated circle, sparsely sparsely populated, and the stomach of the digestive system is developed with a pyloric caeca, and the intestine is short, which is a typical type of meat.
The annual weight of the Australian worm beetle is 200g, the body is up to 230mm, the weight in two years is 800g, the body is up to 350mm, the weight in three years is 2kg, and the weight is up to 500mm.
4 Living habits The worms like to live in backlit areas often live in shaded areas of aquatic plants. Industrial planting should also pay attention to shading. Every summer, especially in summer, the night is the most active. It is light-sensitive during the day, and it is mostly on the edge of the water. Ingesting other small fish, small crustaceans, and sometimes waterfowl, frogs, water mice, etc., will also eat themselves. In the facility fishery, small wild fish or artificially prepared hard pellet feeds may be fed, and soft pellets may also be prepared by mixing the small trash fish with auxiliary materials. Feeding artificial feed should be domesticated from juvenile fish. Temperature range of 7 ~ 30 °C, the optimal growth temperature of 18-22 °C, pH5.5-8.5, the minimum dissolved oxygen is 2mg / L.
5 Farming methods In intensive farming in Australia, circular fiberglass fish ponds are used, which are automatically aerated, aerated, drained, and closed. The water for fish farming is filtered by stainless steel automatic drums, disinfected by biochemical towers and ultraviolet rays, and the light is controlled. The stocking density can reach 10 kg/m3.
The entire fish farm is completely controlled by computers and is supplied exclusively by the feed processing plant for the production of pellets. If the stocking density is reasonable, the water temperature is constant, the dissolved oxygen is sufficient, and the hard pellet feed made by scientific formula is fed, the feed coefficient is 1.3-1.5, and the output can generally be as high as 50 kg/m3. The outdoor earth pond breeding can also obtain good benefits, and it can grow up to 800g/tail for 12 months. Artificially formulated hard pellet feed requires crude protein ≥ 45% and fat ≥ 15%.
6 Propagation In Australia, the worms nestle in natural waters and spawn on their own. After many years of research, they can also be artificially propagated. In the past ten years, the techniques of artificial propagation and production of seedlings are more certain. Usually, the weight of 2.5-4.0kg/tail in 4th to 5th ages is mature, and the eggs can be laid at temperatures above 21°C. The breeding season is usually a mating of females and multi-tailed males in safe shelters or sheltered waters. After spawning, the males disperse the females and take care of their eggs. They swim from time to time to ensure smooth water flow and ensure the hatching progresses smoothly until they emerge. Under 20°C water temperature, the fertilized eggs hatched after 5-7 days. The freshly seeded shoots were 5.0-8.0 mm long. The yolk sac was clearly visible. After 8-10 days, the yolk sac was absorbed and began feeding. Small zooplankton, when the fry develops to 15-20mm in 4-6 weeks, it is used to feed aquatic insects, nematodes, and small crustaceans. Females weighing 2.5-3.0 kg can lay 10,000 eggs, females weighing 5.0 kg lay eggs at 14,000-30000, females weighing 23 kg can lay eggs at 900,000. In the spring when the water temperature is above 20°C, HCG oxytocin is injected to maintain the water temperature at 21°C. After 48-50h, eggs can be laid. The egg is viscous and the average egg diameter is 3-3.5mm. Fertilized eggs were collected in a special collection box. The egg box is 110mm long and 500mm high is hexagonal. The hatching box is moved to a hatching tank with a constant heat and water flow. The hatching rate can reach 90%. When the fry's specifications reach 25-30mm, it is fed with artificial compound feed. The hard granule feed specifications for intensive bred farms in Australia are produced according to the size of the fish. The appearance of hard granule feeds is brown, bright, gives a feeling of a lot of oil, smells like a fish, and the total amount of feed amino acids is close to 43%. The ratio of crude protein in the bait formulation is not less than 50%, and additives and appropriate amount of fish oil are added. According to reports, the feed ingredients are similar to Atlantic salmon.
7 Disease conditions Geranium has a strong resistance to diseases, and its origin is mainly invasive fish disease, in addition to infectious fish disease. The most harmful is Ichthyophthirius multifllils. The water temperature at the time of onset is 12-27°C. Sometimes in hatchery ponds, the seedlings are too dense. Once the food supply is in short supply, the dissolved oxygen is less than 3. At 5 mg/L, larvae may die in large numbers due to the invasion of small melons. In addition, trichodina sp. disease (Trichodina sp) is the peak period of invasive seedlings from October of each year to March of next year, and often causes a large number of deaths. Chilodonella hexasticha can not be ignored. Tartarobasis occurred in a fishing station in inland Australia. The mortality rate was as high as 24%. Others, such as the Apiosoma sp., and Lernaea sp., which are parasitic crustaceans, also occur from time to time. The source of infection is from wild salmon. It should not be overlooked that worms in the breeding process and broodstock eggs in winter can easily be infected with Saprolegnia sp. Viral fish disease is mainly caused by EH-NV virus suffering from hemorrhagic gangrene disease.
The fish disease prevention and treatment drugs in Australia are similar to those in China. Until now, malachite green is still in use. Formalin is a commonly used drug. Fish is often bathed in NaCI solution during aquaculture. New Wales, Australia, used 40 mg/L of formalin to control the trichodiasis of the larvae of P. falciparum, which was deemed to be ineffective and was later used 0.04 mg/L malachite green Quanchiposa. success. Some researchers believe that the disease is caused by Saprolegnia and Achlya in the fungus family. The reason for this is that the operation is not carefully performed during the process of pulling and transporting the fish, resulting in scale or abrasion. . In order to avoid inadvertently causing illness, anesthesia is used for transport of fish, and Benzocaine is used at a dose of 20 mg/L. If heavy anesthesia is required, the dosage is 50 mg/L. At the same time, the brooded fish are used before entering the pond. 0mg/L. Methyl blue bath, isolation quarantine not less than 48h, and then a further 1% NaCl solution bath. For broodstock severely infected with water mold, 2% concentration of malachite green or saturated potassium permanganate solution can be applied to the affected area. For example, in the hatching stage, the fish eggs, after the fertilized eggs are swollen, are filled with 0.2% malachite green and filled into the water pipe. The dropping method is used until the dropping of the medicine is stopped. In the history of the breeding of Tarantula moschata, we have also found Aeromonas hydrophila-induced surface ulcers. Australian experts believe that most of the ulcer diseases are directly related to factors such as poor water quality and improper management. It is generally believed that Maintaining good water quality in quail culture, maintaining sanitation conditions for fish farming facilities, strengthening scientific management, and enhancing fish's own disease resistance will inevitably reduce the spread of diseases.
8 Immersion prospects Through field trips, the overall impression is that A. falciparum has a wide range of tolerance to water temperature and adapts to all inland waters there. The feed conversion ratio is 1.05, which is more suitable for intensive cultivation. There have been several domestic introductions of worms, such as the Qingdao Kunhua Seedling Company and the Jiangsu Provincial Freshwater Fisheries Research Institute. The practice shows that this fish can be scaled up in China, and special attention should be paid to the control of artificial feeding and the control of light during early feeding. The nutritional value of worms and fleas is better than that of razor clams, and its economic value far exceeds that of Wuhuan; in some respects, it also exceeds that of squid. If the artificial breeding on the basis of successful introduction is solved as soon as possible, and it is self-sufficient in seed, it is no doubt that the worm beetle is an excellent breeding new species with good prospects for development in China. It has already begun to take shape.
Source: Freshwater Fisheries Author: Han Maosen
The Biological Characteristics and Implications of Adoptive Worm-worm in Australia
Han Maosen (Department of Aquatic Biological Sciences and Engineering, College of Marine Sciences, Yantai University, 264005)