Fish Diseases Transmitted to Humans

Updated April 21, 2020
Author: Adrian Lawler, Ph.D.
Social Media:

Notes from a talk given to the Saltwater Enthusiasts Association of the Bay Area (SEABay)
(retired) Aquarium Supervisor (l984-l998) J. L. Scott Aquarium Biloxi, MS

...Finally, in this short presentation, I would like to briefly discuss fish tank diseases that can be transmitted to humans. Some can be difficult to cure and some diseases can be quickly FATAL.

Fish TB (MYCOBACTERIUM MARINUM), also called fish tuberculosis, fish tank granuloma, swimming pool granuloma. Related to human TB and leprosy.

Bacteria are very resistant to treatment. Usually occurs on extremities (hands, feet). Entrance through wounds. Incubation ranges from 2 days to 2 years; usually takes about 2 weeks for granuloma to appear at site of infection. Infected area may be pink to purple in color, may discharge pus, and may be painful to touch.
Treated with human TB drugs (local doctors have used minocycline, rifampin, ethambutol, and biaxin); can take a long time to cure (year or more).
People have gotten fish TB from fish spine punctures, cleaning fish/shrimp/crabs, getting scratched on fish tanks, from rose bushes and injuring bare feet in parking lots (infected water transferred via air during storms), mouth-siphoning fish tanks, dolphin bites, diving around reefs, splinters from fish net handles, etc. - Usually not fatal. Can get into joints and mimic arthritis or carpal tunnel syndrome.
Most frequent type of aquatic infection seen in my area.

VIBRIO infections.

Several species can infect humans: V. ALGINOLYTICUS (wound infections), V.DAMSELA (wound/systemic infections), V. PARAHAEMOLYTICUS (gastroenteritis/wound infections),V.VULNIFICUS (wound/gastroenteritis/systemic infections).
Systemic infections with vulnificus or damsela can be rapidly FATAL, or lead to limb amputation.. Systemic infections gotten through wounds.
Incubation of vulnificus is 1-5 days; median time is 28 hours. Symptoms include high fever, chills, nausea, vomiting, diarrhea, abdominal pain, low blood pressure, seizures, fluid-filled skin lesions, etc.
Gastrointestinal infections via ingestion of vulnificus (eating raw oysters, etc) and other species of Vibrio can cause rapid dehydration, and can lead to systemic infections if bacteria enter blood. Vulnificus can multiply so rapidly that blood vessels and organs get clogged...sometimes leading to amputation or death. - Antibiotics utilized have been tetracycline, ampicillin, penicillin, gentamycin, etc. (Also see Dr. Bingman's paper of 4/6/97 at REEFS LIBRARY).

More Fish Disease Info

ERYSIPELOTHRIX RHUSIOPATHIAE, also known as erythema migrans, fish-handler's disease, fish poisoning, fish hand, sealer's finger, whale finger, blubber finger, etc.

Disease primarily occupational .....people handling animals or their wastes can get it, e.g.: butchers, meat-processing workers, animal caretakers, farmers, fishermen, veterinarians, cooks/housewives, sewer workers, etc. Can persist in frozen meats.
Incubation 1-7 days. Fever, malaise, pain in muscles & joints, severe headaches. Infections can go internal to C. nervous system/heart. Most commonly seen on hands-can lead to acute arthritis of finger joints.
Bacterial infection through break in skin. Carried by many animals, including dolphins, shellfish, and fish. - Also known as "diamond skin disease," where diamond-shaped welts occur on the skin due to infection.
Effects usually benign, but can be fatal. Systemic treatment is with antibiotics.

SALMONELLA... over 1600 serotypes identified.

Infection by ingestion. Carried by many types of animals.
Mild to severe gastroenteritis. Can by fatal thru rapid dehydration, septicemia, fecal infections.
Incubation is 7-72 hours.

MAD FISH DISEASE ... caused by STREPTOCOCCUS INIAE.

Recently reported from handling tilapia. Infection via puncture wounds.
Can cause fever, shaking, meningitis, arthritis, and skin/blood infections.
To protect yourself - do not handle organisms/water/tanks if you have skin breaks; do not dive if you have skin breaks; do not mouth-siphon tank water, do not ingest raw seafood, etc. Wash hands, etc. well after working on tanks, with seafood, and after diving. If punctured, or injured under water, allow the wound to bleed freely for a while to expel injected bacteria, then sterilize and protect wound.

Those people with weakened immune systems are at greater risk for getting the above infections. So people with AIDS, diabetes, liver dysfunction, kidney problems, or undergoing cancer treatment, etc. should be especially careful. (SEE: Hubbert et al. Diseases Transmitted from Animals to Man. Charles C. Thomas, Publisher. ISBN 0-398-03056-1)

Toxins produced by RED TIDE organisms and PFIESTERIA PISCICIDA can affect humans in various ways.

PFIESTERIA exposure can lead to skin sores, memory loss, narcosis ("drugged" effect), reddening of eyes, severe headaches, blurred vision, nausea/vomiting, difficulty in breathing, kidney/liver dysfunction, severe cognitive impairment (can't remember name, address, etc), etc.
Relapses have happened 6 years after initial exposure.
PFIESTERIA is now classed as a BIOHAZARD III, and can be researched only in specially-equipped labs.

For more information, please contact: Dr. Adrian Lawler, Aquarium Supervisor (1984-1998, retired), JL Scott Aquarium, Biloxi, MS 39530 (alawler@hotmail.com)