Любомир, спасибо за ответ, но они выглядят не так, как Lernea, а как Piscicola geomtra:
This is the most common fish leech that is found in garden ponds. Whilst being a parasite it differs from Anchor Worm (Lernea) and Fish Louse (Argulus) as it only attaches to the host fish to feed, dropping off afterwards and hiding at the bottom of the pond in order to digest it's meal.
It can survive for long periods without feeding. Piscicola geometra is often introduced to ponds on plants.
Being clearly visible without magnification, it measures up to 25mm in length and appear to be pale brown, or brown and white striped, in colour. Piscicola geometra is a strong swimmer and can move rapidly across the pond searching for it's next host
А чем с ней то бороться?
http://www.pond-life.me.uk/fishhealt...lageometra.php - тут написано, что можно использовать: Dimilin, Masoten and Malathion, но в какой пропорции?
Деревовидний вигляд