Tench

Systematic position: The tench (Tinca tinca) belongs to the order Cypriniformes and the family Cyprinidae. While often considered a freshwater sport fish, its presence in managed irrigation systems, drainage channels, or flooded agricultural fields can interfere with standard agrotechnical operations.

Crops affected: The species primarily affects crops grown in aquatic or semi-aquatic environments, such as rice paddies or specialized wetland crops. It may cause damage to the root systems of young plants and disturb the soil substrate during its foraging activities in muddy, shallow waters.

Biology and development: Tench are bottom-dwelling fish that thrive in silted, slow-moving waters. They possess a high tolerance for low oxygen levels, which allows them to persist in irrigation infrastructure where other species might struggle. Their breeding cycle is synchronized with seasonal water levels, often coinciding with critical growth periods for crops.

Nature of damage and harmfulness: The primary harm stems from the fish's constant digging in the substrate, which leads to physical damage to plant roots and contributes to water turbidity. Increased turbidity reduces light penetration, which is vital for the health and productivity of submerged or floating agricultural crops.

Protection measures: Integrated management strategies to mitigate potential damage include:

• Installing fine-mesh screens on irrigation inlets to prevent fish entry.
• Regular dredging and maintenance of drainage channels to remove silting.
• Implementing periodic draining of paddies to interrupt the fish life cycle.
• Utilizing biological management by introducing natural predators into the system.