Is your fish tank making you sick?

Zoomer | May 1st, 2006

While fish may seem the least threatening of pets, fish owners should still take care when cleaning or handling their finned friends. Ornamental fish tanks are a reservoir for multidrug-resistant Salmonella Paratyphi B dT+, a cause of gastroenteritis in humans, especially young children, according to a study published in the March issue of Journal of Emerging Infectious Diseases, an Australian periodical.

Researchers found that bacterial infections, traced via DNA analysis to fish tanks in the patients’ homes, were serious enough to send children to the hospital with high fever and bloody diarrhea. The bacteria is resistant to a number of drugs, including ampicillin, chloramphenicol, streptomycin, and tetracycline, making it harder to treat.

Symptoms of Salmonella infections typically include cramping, vomiting and/or diarrhea. While infections are rarely serious enough to require treatment with antibiotics, young children, pregnant women, the elderly and others with weakened immune systems are at greater risk of developing more serious or even fatal Salmonella infections.

The scientists concluded that because 12 to 14 pecent of Australian households have ornamental fish and as many as 12 million American and 1 million Canadian families own domestic aquariums, the risk of contamination from the tanks is a public health issue.

The study also notes that the risk of being contaminated by Salmonella bacteria from pet reptiles, ducklings, chicks, and other animals has been recognized for decades.

The December issue of The Canadian Journal of Public Health also carried a paper investigating the link between Salmonella infections and maintaining an aquarium. A survey of 53 people found that 60 per cent of people who had a Salmonella paratyphi B infection had bought tropical fish or had contact with an aquarium before becoming ill.

The study also suggested that more than 50 per cent of the samples taken from fish tanks in homes, pet shops, and wholesaler operations contained other types of Salmonella bacteria.

Dr. Colette Gaulin, who was part of the team behind the study, said health workers in Quebec have developed posters and brochures with safety tips on maintaining an aquarium for distribution to consumers at local pet shops. According to a report in The New York Times, safety precautions include replacing one-third of the tank’s water twice each month and strictly following manufacturer’s guidelines regarding filtration.

Thorough hand washing with soap and water after handling tropical fish and aquarium water is also recommended, as well as maintaining close supervision of young children around aquariums.

Fish owners are also advised to avoid washing aquarium accessories in the kitchen or bathroom sink. If there is no other option, surfaces can be disinfected with a bleach solution of four tablespoons per liter of lukewarm water.