Parasitism by copepods and crustaceans parasitic on sharks

What is it?

Parasitism by copepods and other parasitic crustaceans is a common condition among sharks, including the tiger shark (Galeocerdo cuvier). These small crustaceans cling to the skin, gills, fins or eyes of the shark to feed on its tissues, blood or mucus. In wild sharks, a moderate parasite load is often well tolerated. It becomes a concern in captivity (aquariums, research tanks) or when the animal is already weakened, where the infestation can intensify quickly.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

The infestation is due to various parasitic crustaceans, notably copepods (such as certain genera of the Pandaridae or Dinemoura family) and sometimes isopods, which attach themselves to the external surface of the shark. These organisms use mouthparts or hooks to attach securely to the skin, fins, or gills and feed on the host's tissues or fluids.

Sharks living in captivity or in closed tanks are more exposed, because parasites can multiply more easily in a confined space with less renewed water.\n\nChronic stress, insufficient water quality, too high a density of animals in the tank or a weakened immune system favor the establishment and proliferation of parasites.\n\nContact with new animals or non-disinfected equipment can also introduce parasites into a previously healthy environment.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

Care is the exclusive responsibility of a veterinarian specializing in aquatic fauna, in conjunction with the aquarium team.\n\nIt may combine antiparasitic treatments adapted to the marine environment, targeted medicated baths and improvement of water parameters (filtration, oxygenation, reduction of density).\n\nIn certain cases, careful manual removal of visible parasites may be considered by professionals trained in handling sharks.

Prevention

Possible complications

A large untreated infestation can lead to superinfected skin lesions, gill discomfort with difficulty breathing, general weakness and increased susceptibility to other opportunistic diseases.

When to see a veterinarian

Prognosis

The prognosis is generally good when the infestation is detected early and treated quickly, with improvement in water quality and appropriate treatment. In the absence of treatment, the animal's condition can gradually deteriorate, especially if infectious or respiratory complications appear.

Frequently asked questions

References

WOAH — Organisation mondiale de la santé animale (ex-OIE)

Content reviewed by the TunisieVet editorial team · Updated 24 September 2026