A Preliminary Study on the Small-Water-Body Aquaculture Technique for the Liaodong sculpin

The sculpin, known by local folk names such as "xiagaizi," "xiageda," "xiàpangzi," and "datouyu." It is distributed in the Dandong Yalu River and its tributaries, the upper reaches of the Biliu River, the upper reaches of the Hun River, and other waters.

In the first half of 2002, Liu Yuanzhi, a farmer from Shalizhai in Fengcheng, boldly contracted the village's "drought-resistant large-mouth well," which had been built during the period of "vigorously carrying out farmland capital construction." It had been abandoned and overgrown for many years, with a shallow pit and little water, covering an area of 6 mu. Based on his family's financial capacity, he invested 4,000 yuan that year, excavated and cleared a small fish pond with a water surface of 2 mu, and carried out ecological small-water-body aquaculture of the sculpin, recovering his costs that same year. The aquaculture situation is summarized as follows:

I. Aquaculture Technical Measures

1. Ecological habits of the sculpin. The sculpin is a relatively cold-tolerant bottom-dwelling fish, mostly living in the middle and upper reaches of valley rivers and their tributaries with relatively low water temperatures and sandy gravel or pebble substrates. It is relatively scarce in river channels with sandy bottoms and mud. It does not form schools, feeding on small fish, river shrimp, Northeastern crayfish, aquatic insects and their larvae. It is a fish of little activity, usually lying on the river bottom, drilling under stones, and using sudden dashes for short-distance swimming.

2. Pond conditions @#@233@#@ The pond is a "drought-resistant large-mouth well" that had been abandoned and overgrown for many years, with a pebble substrate and solid, well-formed embankments, with a total area of 6 mu. A small water surface of 2 mu was cleared and excavated, with an average water storage depth of 1.5 m and a maximum depth of 2.1 m. The water source is underground spring water, with a water temperature of around 15°C, very suitable for the growth of the sculpin. The fish pond has good water retention capacity, able to remain without drying up in dry weather and without flooding in the rainy season, with flexible drainage and irrigation regulation. Outside the embankments there are 4 mu of riverbank land, planted with two thousand black locust trees to prevent soil erosion.

3. Water quality requirements. The sculpin is suitable for aquaculture in lean-water-type ponds, with water quality maintained as lively, soft, and refreshing, with sufficient dissolved oxygen, and a deep duck-egg-shell green color. There is no need to excessively fertilize the water quality.

Before releasing fry, old ponds must be thoroughly cleared of rotten grass and mud. Depending on the specific situation, an appropriate amount of river pebbles should be placed in the fish pond, which is beneficial to the growth and development of the sculpin. The pond water should be maintained at a depth of around 1.5 m.

4. Releasing fry. Fry were released in mid-April 2003. The fry mainly came from natural wild fish species, and 600-700 fish can be released per mu of water surface. Using fishing nets to catch fish easily injures the fish body, and the damaged skin membrane areas easily breed cotton-like Saprolegnia hyphae, which then spread successively, ultimately leading to diseased and dead fish. To treat this disease, a mixed solution of 5% salt water and baking soda (1:2) can be used to soak the fish body for 4-5 minutes before releasing into the pond.

II. Daily Feeding and Management

1. Water quality regulation. In daily production, maintain good pond water quality, a deep duck-egg-shell green color, and water transparency of around 25 cm. Persist in patrolling the pond once each morning and evening, and promptly remove dead grass and rotten leaves from the fish pond. The pond should maintain a high water level. It is best to keep a fish-farming diary, continuously accumulate experience, and raise the level of scientific fish farming as quickly as possible.

2. Feeding bait. The bait is mainly live small river fish, small river shrimp, and aquatic insects, with no artificial compound feed, for the purpose of cultivating the wild nature of the sculpin and maintaining the deliciousness of its flesh. After the busy spring season in May ends, it is precisely the rapid period of reproduction, growth, and development for the sculpin. Farmers can use their slack time to catch more small fish and aquatic insects in the river to ensure bait supply.

3. Protective measures. Because baiting is mainly with live organisms, there are very few leftover bait residues, and the probability of fish contracting disease is greatly reduced. However, it is still necessary to prevent disease early when there is none and treat it early when there is, combine pond clearing, replace old water with new water at the appropriate time, and appropriately apply quicklime to sterilize and kill insects in the pond.

Prevent ducks, geese, and wild birds from harming the fish pond. During the flood season, take care to prevent pond water from overtopping the embankments. At the same time, pay attention to changes in the pond water quality and fish activity, and if problems are found, take targeted measures for remediation.

4. Timely harvesting. Before the rivers freeze over in the Liaodong region each year is the season when the sculpin is fat and delicious. At this time the fish price is relatively high, so timely harvesting should be carried out. Sort by size: sell the large ones and keep the small ones as seed stock. During harvesting, pond clearing can be combined with removing weeds and mud, maintaining a water depth of 1.5-2 m, to prepare for the safe overwintering of the fish pond.

5. Safe overwintering management. In past fish pond overwintering management, people often adopted methods such as cutting ice holes and piling firewood and grass on the water surface before freezing to form ice holes, to increase oxygen in the overwintering fish pond. Practice has proven that the oxygen-increasing effect of this method is negligible. Moreover, cutting ice holes easily frightens the fish school, causing injury to the fish body, and piling firewood and grass easily pollutes the fish pond. Maintaining water depth is the key to safe overwintering of the fish pond.

III. Aquaculture Results

After more than 240 days of aquaculture, the maximum fish weight was 0.5 kg. The yield per mu of fresh finished fish was 53.4 kg, achieving a benefit of 2,136 yuan per mu. After deducting the cost of excavating the fish pond that year, there was still a slight surplus.

IV. Summary and Discussion

1. The natural individual size of the sculpin is small. It has been found that the largest individual at 4-5 years old is about 0.15 kg. Through artificial aquaculture, fry at 2-3 years old can increase to 0.25 kg in 7 months, and the largest individual can reach 0.5 kg in weight. Artificial aquaculture grows faster than natural growth. The flesh of larger sculpin is in a garlic-clove shape, with good meat texture and taste, and is especially marketable, reaching more than 70 yuan per kg.

2. Fish ponds cannot be selected with a mud substrate. During the aquaculture process, do not excessively fertilize the fish pond or feed artificial compound feed; otherwise, the fish body color turns black, and the flesh becomes fishy and loose, with no market. If the fish pond has a sandy gravel substrate, an appropriate amount of river pebbles should be added when building the pond.

3. Carp, grass carp, and others can be polycultured in sculpin ponds.