Parasites: Carp lice

Argulus foliaceus, or carp louse, is a crustacean (crustacean) belonging to the Branchiura class. Crustaceans are multicellular, animal-like, egg-laying organisms that reproduce sexually. The name carp louse is somewhat misleading, as it can also occur on numerous other fish, including brackish water fish. However, it prefers cyprinids, which also include goldfish.

Infection

Argulus is often introduced into ponds by feeding live food caught in a water where cyprinids are present, by adding plants or stones from another fishpond, or by introducing new (infected) fish. Theoretically, eggs could also be spread by migrating animals.

Description

The Argulus has a vicious stinger. Located between the eyes, it can be fatal to a small fish with a single sting. The carp louse attaches to the fish with two suckers and numerous other extremities, piercing the fish's epidermis with its stinger. It then injects venom and sucks in tissue and blood. The wounds left behind are difficult to heal and can be a source of secondary diseases.

Features

Argulus can be described as a transparent, greenish crustacean with black spots. It has an oval, flattened body with two large eyes. It has eight legs (four pairs) and a bisected abdomen that functions as a rudder. Using these bristly legs, the carp louse is able to swim from one fish to another and can also propel itself across the fish's body. The creature is visible to the naked eye and can grow up to about eight millimeters in size. Microscopic examination is recommended.

Cycle

The life cycle, like that of many other coldwater parasites, is highly temperature-dependent. After mating on the fish's body, the female leaves the fish and lays 100 to 400 lemon-yellow eggs on solid objects and plants in the pond. The female then dies. After a few weeks (depending on the temperature), the eggs hatch. The fry swim freely during the first phase of their lives. Only after several molts do the females seek out a host (fish). They parasitize this host until they reach sexual maturity after about two months.

Treatment

For a small number of cases, I prefer a biological method. Apply pure alcohol or saturated saline solution to large specimens (use a cotton swab). Then remove them with blunt tweezers. This allows you to break the cycle. In the case of a massive infestation, pesticides will be necessary. Be careful with this, as these are dangerous and harmful substances.

Author: Joop van Tol (www.koitoday.nl)