Experience in raising loach with crab

Raising loach and crab in rice fields is a new and promising direction, attracting many people's attention because it requires little investment, is easy to raise, is almost disease-free, and has readily available food in nature.

Fields for raising loach and crab

1. Biological characteristics of loach and crab

- Loaches have the habit of living in the mud.

- Field crabs crawl on the bottom of the water and dig holes to live or burrow into bushes and roots of aquatic plants. Crabs can crawl on land and move very far, each time they molt their weight increases from 20-50% of their potential weight.

- These two species have in common the characteristic of being nocturnal, not liking strong light, so during the day they only stay in caves or hide in the mud, rarely going out, only when it is dark do they go out to find food. Their main food is shrimp, prawns, miscellaneous fish, worms, snails, grains... The water temperature can grow and develop from 20-30 degrees Celsius, best from 25-27 degrees Celsius, pH from 6.5-8. In the rainy season (from March to August every year), field loach and field crab grow, develop strongly and reproduce a lot.

2. Prepare the field

For loach and crab to grow and develop well and not be lost, the farming field must be well prepared before releasing the seeds.

- Choosing farming fields: Flat fields, good water retention, abundant water source, convenient water supply and drainage, unpolluted water, loamy soil.

- Farming field area: Depending on the conditions, the suitable farming field area is from 3,000 - 5,000m2. After harvesting, the winter-spring rice is cut to leave long straws, which are rice straws, to be used as food for loach and crab. Then, water is pumped into the field to a height of 0.5 - 0.7 meters.

- Dig a surrounding ditch and a middle ditch. The ditch around the foot of the bank is 0.8-1.0m deep and 3-5m wide. If the field is wide, dig an additional “+” or “#” shaped ditch in the middle of the field, 1-1.5m wide and 0.5-0.8m deep. The total area of ​​all 3 types of ditches accounts for about 15-20% of the field area.

The purpose of digging ditches in the fields is to create shelter for loach and crab during hot, cold weather or unusual changes in the environment.

- The field banks must be made high and large. Pay attention to compacting the soil to avoid water leakage. The water supply and drainage gates must be covered with bamboo nets or suitable fishing nets, and the sewer base must be compacted.

- Place a net around the field. If the net is made of thin nylon, you must drive the stakes 40-50cm higher than the bank surface. Use steel wire to tie the ends of the stakes together. Fold the nylon sheet over the steel wire so that it hangs down to the ground in 2 layers and then bury it 15-20cm deep in the bank soil. If you use a plastic sheet or fibrocement sheet, you only need to bury it 15-20cm deep in the ground, with the top end at least 40cm higher than the ground, with the four corners curved in an arc. This is to prevent rain from flooding the bank, causing loach and crab to go out.

- Plant water grass to cover the bottom of the ditch and release floating plants such as duckweed, water hyacinth, water spinach… to about 1/3 of the water surface. To provide shelter for loach and crabs during hot or cold weather.

- If possible, make an additional bank for loaches and crabs to dig holes and take shelter. The bank should be about 1 meter wide and 30-40 cm higher than the water surface at its highest point. Sprinkle mulch on the bank to help crabs and loaches avoid the sun and cold when the outside temperature changes. Therefore, the wider and more solid the bank is, the later when the mulch is good and the roots develop, the wind will not cause the bank to collapse. At the same time, the loaches and crabs will have less impact on the main bank around the farm. Depending on the shape and size of the farm, the bank can be made in the shape of a cross or parallel.

- 1-2 weeks before raising, drain the water to kill all the enemies of loach and crab and destroy pathogens by applying lime 7-10 kg/100 m2, drying in the sun for 3-5 days, then add water but do not let the water overflow into the field, only when the rice is about to form ears, add water to the field so that the crabs can come up to the field to find food.

- Use manure or chemical fertilizers to color the water to create a source of zooplankton to grow as food for newly released crabs.

3. Select the breed

Currently, there is no facility on the market that specializes in artificially producing loach and crab breeds. To get the breeds, farmers can order them from traders. When buying, you need to pay attention: Choose to buy at trusted addresses, ensuring the quality according to requirements.

+ Field loach: healthy, uniform size 150-200 loach/kg, shiny, not slimy, swims actively, no scratches. Do not buy at the market if not careful, you can easily buy the wrong loach that has been electrocuted, has damaged spine, crooked body, does not grow when raised and reduces economic efficiency.

+ Field crabs: healthy, uniform size 150-160 crabs/kg, no broken claws or cuffs, shiny shell, no algae.

4. Release the seeds

- The suitable release season is March-April every year. Release in the early morning or cool afternoon.

- The density of stocking rice field eels and rice field crabs: 20 fish/m2 is suitable, in which

+ Loach: 16 fish/m2

+ Field crabs: 4 crabs/m2
Only need to release the seeds once, the following crops do not need to release more because the loach and crab will reproduce themselves in the farm.

5. Care

Loach and crab are species that are very resistant to environmental conditions, almost disease-free. Natural food is very available such as: golden apple snails, we can take advantage of this food source very well because the protein content in golden apple snails is quite high. In addition, we can use food: shrimp, prawns, minced fish, fish meal, rice bran, corn bran, rice husks, tapioca flour...

We can make our own mixed pellet feed including: ground rice + fish meal + golden apple snail. Then put it in a pellet press and dry it for the loach and crab to eat gradually.

- Feed 1-2 days after releasing the seeds. Initially, feed evenly throughout the field, then gradually reduce the feeding area, and finally feed at a few fixed points in the field so that the loach and crab get used to eating, making it easier for the harvest process later.

Feeding method: Protein food and concentrated food are fed together, fed once every 2 days at a fixed time in the evening. The amount of food is about 5% of the body weight of the crab or loach.

In addition, you can add organic fertilizer with the amount of 25-30 kg/100 m2 of field/month to help zooplankton in the field grow as food for loach and crab.

Note: In feeding areas, feed trays made of very small mesh should be placed at the bottom of the field, the area of ​​the feeding tray should be about 1.0-1.5 m2, then feed should be put into the tray. The next morning, check the amount of excess feed to have a plan to adjust the feed accordingly. Because loach and crab are mainly nocturnal species, feed in the evening, feed in the fishing area. Depending on the evaporation level, regularly add more water to the field to keep the water environment clean, regularly maintain the water level of 0.5-0.7 m. Pesticides should absolutely not be used in the field.

6. Harvest

After about 4-5 months of raising, you can proceed to harvest. After 5-6 months, the loach reaches 20-25 gr/fish, the crab reaches 25-30 gr/fish. You can harvest partially or completely.

Stop feeding 1-2 days before harvest.

- Harvesting: place a basket containing bait such as rice bran or cleaned golden apple snails in the feeding position. Place the basket in the evening of the previous day, early the next morning, scoop out the basket, collect the big ones, release the small ones to continue raising.

- Collect all the water used to harvest field loach: Drain the water slowly so that the field loach can swim with the water flow. Place a net or basket at the drain to collect the loach.

Farmers should only harvest a portion, and choose the large and healthy ones to raise in the field to reproduce for the next crop.

According to the National Agricultural Extension Center