Using chemicals to kill snails in shrimp ponds.

In shrimp ponds (square ponds), the most common type of snail is the periwinkle snail. To control and eradicate this type of snail, several points need to be considered simultaneously.

Harmful effects of snails

Snails in ponds can act as vectors for many diseases transmitted to shrimp; they can also compete with shrimp for food and habitat. In particular, a large number of snails can lead to a decrease in alkalinity in the pond because snails absorb calcium from the water, which can cause calcium deficiency in shrimp, resulting in soft shells and difficulty molting.

Applying lime and drying out the pond kills snails and their eggs - Photo: Tran Ut

Methods for preventing and treating snail infestations.

- Thoroughly prepare the pond, apply lime, and dry it out to ensure all snails and their eggs are eliminated.

- Take water during high tide, carefully filtering it with a mesh filter before supplying it to the pond. The bag should be made of double-layered cotton fabric, 8-10 meters long and 0.6 meters in diameter.

- The water is left in a settling pond for 5-7 days to allow all the eggs and larvae to hatch, then treated with chlorine at a rate of 10-15 kg/1,000 m³ or formaldehyde at a rate of 20-30 liters/1,000 m³. After that, it is left for 24-48 hours before being pumped into the rearing pond. Before pumping, shrimp must be tested to ensure that these substances have decomposed or evaporated completely.

- During the rearing process, if there are snails, you must periodically remove them (be careful not to cloud the water). Catching snails manually is as follows: Observe the snails' feeding habits, when they are most active during the day, and whether they usually congregate at the bottom or edge of the pond; then try scattering bait to lure them to the edge of the pond and catch them with a net or your hands.

Use nets to catch snails by putting small pieces of food (smaller than shrimp food) into the net, waiting for the snails to come in to eat, then scooping them up and catching them gradually. Alternatively, use bamboo mats placed around the pond. Snails like to cling to this substrate, but note that initially you must observe whether it affects the shrimp.

Daily checks and removal of snails are relatively effective in ponds used for shrimp farming.

According to (Vietnam Fisheries) - LC