Bacterial Skin Infection in Shortfin Mako Shark
Bacterial skin infection in the shortfin mako shark is a skin disease caused by bacteria that take advantage of a wound or weakened immune system to develop. It mainly affects mako sharks kept in captivity, in aquariums or tanks, where stre...
What is it?
Bacterial skin infection in the shortfin mako shark is a skin disease caused by bacteria that take advantage of a wound or weakened immune system to develop. It mainly affects mako sharks kept in captivity, in aquariums or tanks, where stress and contact with walls can create small wounds. This disease remains rare in the wild because it is closely linked to captivity and transport conditions, which are particularly challenging for this pelagic species that is sensitive to stress.
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 often include areas of damaged, reddened or discolored skin, sometimes with a whitish or opaque appearance around a wound.
Lesions may appear as small ulcerations that do not heal normally, sometimes accompanied by a deposit or film on the skin.
The shark may swim abnormally, rub against the tank walls or floor, or conversely become lethargic and move less.
In advanced cases, loss of appetite and general lethargy may appear, a sign that the infection is spreading or that the shark's overall condition is deteriorating.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Several types of bacteria naturally present in seawater can become pathogenic when the shark's skin is damaged. These opportunistic bacteria take advantage of a wound, abrasion or weakened immune defenses to colonize the skin and cause a localized infection, which can then spread if left untreated.
The shortfin mako shark is a species particularly sensitive to the stress of capture and captivity, which makes its skin more vulnerable. Injuries during transport, rubbing against walls in an undersized tank, poor-quality or poorly filtered water, inappropriate temperature or salinity, and an immune system weakened by stress are the main factors that promote the onset of this infection.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Diagnosis is established by a veterinarian specializing in aquatic or exotic animals, who observes the skin lesions and may take a sample to identify the causative bacterium in the laboratory. Water quality analysis of the tank is also recommended to identify any contributing factors.
Treatment
Treatment may include antibiotics suited to the aquatic animal and administered according to protocols determined by the specialist veterinarian, as well as local wound care. Improving tank conditions (water quality, space, stress reduction) is an integral part of management.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention relies first and foremost on suitable captive conditions: tanks large enough to allow continuous swimming without contact with the walls, water quality strictly monitored, and minimal handling of the animal to reduce stress and injury. Regular skin checks allow early detection of any lesion before infection develops.
Possible complications
Without treatment, the infection can spread deeply into subcutaneous tissues and lead to generalized infection (septicemia) that threatens the animal's life. Stress from the disease can also worsen the animal's overall condition, particularly given that mako sharks tolerate prolonged captivity very poorly.
When to see a veterinarian
Appearance of any lesion, wound, or abnormal skin area on the shark.
Change in swimming behavior or repeated rubbing against the walls.
Loss of appetite or unusual lethargy.
Rapid worsening of an existing wound or appearance of deposits on the skin.
Prognosis
The prognosis depends on how quickly treatment is started and on improvement in the animal's living conditions. An infection detected early and treated with appropriate care has a better chance of recovery, but the mako shark remains a fragile species in captivity, which can complicate healing even with proper treatment.
Frequently asked questions
Does the shortfin mako shark easily develop skin infections?
Yes, especially in captivity. It is a species very sensitive to stress and injuries, which makes its skin more vulnerable to bacteria present in the water.
Can this infection be transmitted to humans?
No, this is not a disease transmissible to humans under normal contact conditions.
Can you care for a shortfin mako shark like a typical aquarium fish?
No, this species requires care from a veterinarian who specializes in aquatic animals, as its needs and sensitivity are very specific.
Can infection be prevented?
Largely yes, by ensuring an appropriate tank, good water quality, and minimal handling of the animal to prevent injuries.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 24 August 2026
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