Bacterial infection in deep-water pink shrimp
Bacterial infection in deep-water pink shrimp encompasses several diseases caused by bacteria, most often of the genus Vibrio, which attack the carapace, gills, or internal tissues of the animal. This shrimp, caught in deep water in the Med...
What is it?
Bacterial infection in deep-water pink shrimp encompasses several diseases caused by bacteria, most often of the genus Vibrio, which attack the carapace, gills, or internal tissues of the animal.
This shrimp, caught in deep water in the Mediterranean and Atlantic, can be affected both in the wild and in captivity, for instance when kept alive after capture or in experimental farming facilities.
The disease manifests mainly when the animal is weakened, stressed, or injured, which opens the door to bacteria naturally present in seawater.
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:
Early signs are often subtle: the shrimp becomes less active, remains still, or swims erratically.
Refusal to feed and a dull appearance of the carapace may be observed.
Dark, brown, or blackish spots (sometimes called "black spot disease") occasionally appear on the carapace, appendages, or gills, corresponding to areas where tissue is being damaged.
Erosions or small wounds on the carapace, damaged legs, localized swelling, or abnormal gill coloration (which may become brownish instead of remaining clear) are also possible.
In severe cases, the animal becomes very lethargic, remains on the bottom without moving, and death can occur within a few days.
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 disease is caused by bacteria, principally species of the genus Vibrio, but also sometimes other opportunistic marine bacteria such as certain Pseudomonas or Aeromonas species.
These bacteria are naturally present in seawater and become problematic mainly when the shrimp is weakened.
They take advantage of a wound, a recent molt (a period when the carapace is soft and vulnerable), or a compromised immune system to invade the tissues.
Several factors increase the risk of infection: poor water quality (excess organic matter, insufficient oxygen, unsuitable temperature), high stocking density in a tank or pond, stress from transport or handling after capture, injuries sustained during capture or molting, and inappropriate diet.
Animals already weakened by another disease or parasites are also more susceptible.
Transmission
Transmission occurs mainly through contaminated water, direct contact between animals in confined spaces, or by non-disinfected contaminated equipment.
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 observation of clinical signs (spots, lethargy, lesions) combined with analysis in a specialized laboratory.
These analyses may include bacterial culture from the hemolymph (the shrimp's "blood") or affected tissues, as well as more advanced bacterial identification techniques.
A specialist in the pathology of aquatic invertebrates or a veterinary laboratory experienced with aquatic animals is usually needed to confirm the diagnosis.
Treatment
Individual treatment of shrimp is rarely practical, particularly in wild settings or extensive farming operations.
In certain controlled maintenance situations, antibiotics suited to marine bacteria may be considered, but their use must be overseen by a specialist to avoid promoting the development of resistance.
Management relies primarily on improving farming conditions: correcting water quality, reducing stress and stocking density, and isolating affected animals when possible.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention relies mainly on maintaining good water quality: adequate oxygenation, stable temperature, and low organic load.
It is recommended to avoid overstocking in tanks or storage ponds and to limit rough handling that can injure the animals.
Quarantining new arrivals before mixing them with an existing group helps prevent the introduction of pathogenic bacteria.
Regular cleaning of facilities and disinfection of equipment are also useful measures.
Possible complications
An uncontrolled bacterial infection can lead to generalized septicemia—that is, spread of bacteria throughout the organism—resulting in the animal's death.
In farms or ponds, the infection can spread rapidly from one individual to another, causing significant losses across the entire group.
When to see a veterinarian
Observation of several lethargic or immobile shrimp in the same group.
Appearance of dark spots or lesions on the shell of multiple animals.
Repeated unexplained mortality in a pond or tank.
Abrupt change in behavior or generalized loss of appetite in captive-held animals.
Prognosis
The prognosis depends on the stage at which the disease is detected and on the ability to quickly improve farming conditions.
Early detection combined with immediate improvement in water quality often makes it possible to limit mortality.
Conversely, advanced infection with generalized disease usually leads to death, and the prognosis is poor if the infection spreads to the entire stock.
Frequently asked questions
Can this disease be transmitted to humans?
No, the bacteria responsible for this infection in pink shrimp are not considered transmissible to humans under normal conditions of handling or consumption of a properly cooked product.
Can you treat a sick shrimp with antibiotics bought on your own?
No, antibiotic use must always be supervised by a specialist. Inappropriate use can worsen the situation and promote the emergence of antibiotic-resistant bacteria.
How can we prevent the disease from spreading throughout an entire basin?
The best prevention consists of monitoring water quality, avoiding overcrowding, quickly isolating suspected animals, and regularly cleaning facilities.
Do black spots always mean a bacterial infection?
Not necessarily. Dark spots can also appear after mechanical injury or in other circumstances. Only specialized analysis can confirm the exact cause.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 27 October 2026
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