Skin fluke infestation

Overview

Name

Neobenedenia sp. (Capsalidae)

Description

Neobenedenia sp. is a parasitic flatworm that is ubiquitous in the marine environment.

The parasite is endemic to Queensland.

Low seawater temperatures may contribute to Neobenedenia sp. causing disease in barramundi.

Previous disease outbreaks in Australia occurred in winter when seawater temperatures were lower than 20ºC.
 
The flatworm is strictly a marine parasite and is killed by freshwater bathing.

Where the disease occurs

Neobenedenia sp. is known to occur throughout the world, and cause disease in wild, farmed and aquarium fish.

The disease affects most tropical marine finfish with scales.

The disease in animals

Neobenedenia sp. is present on the skin, fins and eyes of their host. Parasites feed on mucus, causing irritation to the host. The host may rub themselves on hard objects to remove the parasites.

Stressed barramundi can be more susceptible to the parasite and low temperature appears to be a factor. High density of fish is another risk factor.

It is a highly effective parasite because it has a direct life cycle (i.e. no intermediate host), and is very mobile over the fish surface.

In dense populations of the susceptible host fish species, Neobenedenia sp. can multiply rapidly.

The parasite thrives in crowded conditions (such as aquariums) and marine aquaculture facilities (such as sea cages).

Symptoms of Neobenedenia

Symptoms may not be obvious; however, initial signs include cloudy eyes (cornea) and pale patches on the skin (excess mucus). As the infestation progresses, the fish will lose scales and its skin will redden due to epidermal damage. 

The parasite can be hard to detect because it is transparent when on the skin.

Neobenedenia and people

Neobenedenia sp. is not known to cause disease in humans.

As a precaution, we recommend that people not eat fish affected by Neobenedenia sp. because the damaged skin may allow water bacteria to enter the body, contaminating the flesh.

Last updated 05 February 2014