parasitic disease Caramote prawn

Roundworm infection of tiger prawns (gastrointestinal parasitism)

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Definition Signs Causes Transmission Diagnosis Treatment Prevention Complications When to see a vet Prognosis FAQ Sources Affected species

What is it?

Roundworm infection of tiger prawns (Penaeus kerathurus) refers to the presence of nematodes (roundworms) lodged in the digestive tract of this shrimp species. This condition occurs mainly in farmed settings (aquaculture) or in wild-caught animals held in tanks. It remains poorly documented overall compared to viral or bacterial shrimp diseases, but it can weaken the animal and reduce growth performance.

Commonly observed signs

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

Related signs — each one links to its page:

Loss of appetite Fatigue Stunted growth Reduction

Signs are often subtle and non-specific in tiger prawns. Reduced appetite, slowed growth, and generally diminished activity may be observed. In farmed settings, this manifests as size variation within a single batch: some individuals grow normally, while others remain stunted. With heavy infestation, the digestive tract may appear altered on examination, sometimes showing visible intestinal distension visible through the transparent shell. There is no clear external sign that allows a non-specialist to confirm the presence of roundworms.

When to consult without delay

This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.

Causes and risk factors

The condition is caused by nematodes (roundworms) that establish themselves in the tiger prawn's digestive tract. These parasites benefit from a life cycle that may involve other aquatic organisms as intermediate hosts before colonizing the shrimp. Infection typically occurs through ingestion of larvae present in the water, sediments, or food (notably when using uncontrolled fresh food sources such as mollusks or fish scraps).

High-density farming systems, degraded water quality, the use of fresh, untreated feed, and the presence of intermediate hosts (mollusks, small crustaceans) in the pond favor the development of this parasitism. Stress from transport or unsuitable farming conditions can also weaken the shrimp's natural defenses and promote the establishment of worms.

Transmission

Transmission occurs through ingestion of nematode larvae present in the water, sediments, or via intermediate hosts (small aquatic invertebrates) consumed by the shrimp.

Diagnosis and care

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

Diagnosis is based on direct examination of the shrimp's digestive contents or intestine, performed by a specialist in aquaculture pathology, often following dissection or microscopic examination. Samples can be sent to a laboratory specializing in crustacean pathology to precisely identify the type of nematode involved.

Treatment

Management focuses primarily on improving farming conditions (water quality, feed, stocking density). In some cases, antiparasitic treatment suitable for crustaceans may be considered, but its use remains supervised by an aquaculture pathology specialist due to shrimp's sensitivity to many substances.

Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.

Prevention

Prevention relies on good water quality management, the use of quality-controlled feed (preferably industrial pellets rather than untreated fresh products), and regular monitoring of herd health status. Limiting the presence of potential intermediate hosts in ponds and avoiding overstocking also help reduce the risk.

Possible complications

Severe untreated infestation can lead to general weakness, stunted growth, and increased susceptibility to secondary opportunistic infections (bacterial or fungal). In farming operations, this results in economic losses due to size heterogeneity and increased mortality if additional stress occurs.

When to see a veterinarian

Unexplained slowing of growth in several individuals in the same pond.

Unusual or unexplained mortality in a farming batch.

Marked size heterogeneity despite uniform farming conditions.

Concern about the health status of a batch before transfer or sale.

Prognosis

The prognosis is generally good if housing conditions are corrected quickly and the infestation is detected early. However, severe and prolonged infestation can compromise growth and survival in the most heavily affected animals.

Frequently asked questions

Are roundworms from Norway lobster dangerous to humans?

No, this digestive parasitism in shrimp is not known to pose a risk to human health. The consumption of well-cooked caramotes does not present any particular problem in this regard.

How to tell if your farmed shrimp are infested? Here are the main signs to watch for: **Visual indicators:** - White spots or patches on the body or shell - Discoloration or darkening of the shell - Visible parasites or worms - Lesions or sores on the body - Abnormal molting patterns **Behavioral changes:** - Loss of appetite - Reduced activity or lethargy - Erratic swimming patterns - Gathering at the water surface - Excessive molting **Water quality issues:** - Sudden changes in ammonia or nitrite levels - Cloudiness in the tank - Foul odor **Population indicators:** - Unexplained deaths - Rapid spread among the colony **Common infestations to watch for:** - Bacterial infections (black spot disease, white spot syndrome) - Fungal infections - Parasitic copepods - Nematodes **Prevention tips:** - Quarantine new shrimp before adding them - Maintain proper water parameters (temperature, pH, salinity) - Avoid overfeeding - Perform regular water changes - Keep the tank clean If you suspect an infestation, isolate affected shrimp immediately and consult an aquaculture specialist for proper diagnosis and treatment.

There is no visible sign perceptible to the naked eye that confirms the presence of roundworms. Only an examination by an aquaculture pathology specialist, using dissection or laboratory analysis, can confirm it.

Can caramotes be treated against these parasites?

Solutions do exist, but they must be implemented with the help of a specialist, because crustaceans are sensitive to many antiparasitic substances. Improving farming conditions remains the primary measure to consider.

Does this parasitism also affect wild shrimp?

Yes, it can be present in wild animals, but it is mainly monitored in livestock farming contexts where its economic consequences are more easily observed.