When female parasites attach to the fish, they burrow deep into the tissues and eventually embed an anterior anchor into the fish's body. Intense focal inflammation and hemorrhage can occur at the attachment site, making the area appear red and ulcerated. While an infection by small numbers of parasites isn't necessarily fatal, it is extremely irritating to the fish. Lernaea can cause intense inflammation, leading to secondary bacterial (e.g., Aeromonas hydrophila) and fungal infections.
A 30-minute bath with 25 mg/L potassium permanganate will kill larval lernaeids, but adults may survive. Diflubenzuron (also known as Dimilin) is a pesticide that interferes with growth of the parasite and will kill molting adult and larval stages at a dose of 0.066 mg diflubenzuron/liter.
After this treatment you can use this: