Bacterial infection in shrimp
Bacterial infection in shrimp encompasses several diseases caused by opportunistic bacteria, such as Vibrio species, which take hold when the animal's immune system is weakened or when water quality deteriorates. The red giant prawn, often...
What is it?
Bacterial infection in shrimp encompasses several diseases caused by opportunistic bacteria, such as Vibrio species, which take hold when the animal's immune system is weakened or when water quality deteriorates. The red giant prawn, often caught from deep-sea fishing grounds, can be affected during experimental farming or when held in tanks. These infections are common in aquaculture settings and can cause significant mortality if left untreated.
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:
Infected shrimp become lethargic and swim erratically, sometimes staying near the surface or lying on their side.
Abnormal coloration of the shell may be noticed, with dark or reddish patches, and occasionally small lesions or erosions on the exoskeleton.
Appetite decreases noticeably, and the animal isolates itself from the group.
In severe cases, mortality occurs rapidly, sometimes without visible signs beforehand, which is typical of acute bacterial infections in crustaceans.
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 mainly by bacteria of the genus Vibrio (such as Vibrio harveyi, Vibrio parahaemolyticus, or Vibrio alginolyticus), though other opportunistic bacteria may be involved. These microorganisms occur naturally in seawater and become pathogenic when the shrimp is weakened or stressed.
Poor water quality (high ammonia levels, low oxygen, sudden changes in temperature or salinity) greatly favours the development of the disease.
Overstocking of tanks, stress from handling or transport, and inappropriate feeding weaken the shrimp's natural defences.
Wounds on the shell, for example after moulting or impact, create an entry point for bacteria.
Transmission
Transmission occurs mainly through contaminated water, by direct contact between animals, or by ingestion of bacteria present in the environment. A weakened or injured animal is more likely to become infected.
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, combined with analysis of the tank water. A veterinarian specialising in aquatic animals or a laboratory can take samples to identify the causative bacterium by microbiological culture or further testing.
Treatment
Treatment relies on immediate improvement of water quality and reduction of environmental stress. Appropriate antibiotics may be used under professional supervision, taking into account regulations governing their use in aquaculture. Immunostimulant or probiotic products may also be offered as support.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Maintaining good water quality, with regular monitoring of parameters (oxygen, ammonia, temperature, salinity), is the foundation of prevention.
Avoiding overstocking and limiting stressful handling reduces risk.
Quarantining new animals before introducing them into a communal tank is recommended to prevent the introduction of pathogens.
Appropriate, balanced feeding strengthens the animal's natural resistance.
Possible complications
Without prompt treatment, the infection can spread and lead to septicaemia, resulting in high mortality in the tank. Poor management can also promote spread throughout the entire stock.
When to see a veterinarian
Observation of several shrimp appearing lethargic or swimming abnormally
Appearance of spots or lesions on the shell
Sudden loss of appetite in the group
Unexplained deaths in the tank
Sudden deterioration of water parameters
Prognosis
The prognosis depends on how quickly treatment is started. If water quality is corrected promptly and appropriate treatment is put in place early, mortality can be limited. Without intervention, losses can be substantial.
Frequently asked questions
Can this disease be transmitted to humans?
No, these bacteria are specific to aquatic environments and do not represent a risk of direct contamination for humans under normal handling conditions.
Can one consume shrimp from a affected pond?
It is advisable to consult a professional before any commercialization, as the presence of bacteria or antibiotic treatments may raise food safety concerns.
How can you prevent the disease from coming back?
Regular monitoring of water quality and proper management of pond stocking density are the best means of preventing recurrence.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 26 October 2026
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