Around the world, private collectors and businesses maintain beautiful fish tanks stocked with colorful corals, speedy little cichlids and stately angelfish. But a hidden danger lurks: many fish that wind up in aquariums carry antibiotic-resistant bacteria that could pose a threat not just to a billion-dollar industry but to human health.
A recent study published in the Journal of Fish Diseases measured 32 different ornamental fish that entered the port in Portland, Ore., from places such as Colombia, Singapore and Florida. The specimen were found to carry 64 different bacterial colonies, and many were resistant to antibiotics to varying degrees. The bottom line: not only were the fish more susceptible to infection, but their bacteria harbored genes that could make them immune to drugs - genes they can pass along.
Resistance to antibiotics can develop in a number of ways, but the most common culprit is overtreatment, a practice commonly used when fish are transported.
The chain of events is pretty easy to follow. The majority of ornamental fish start their lives in Asia and other exotic locations and are shipped all across the globe. Those trips aren’t a walk in the park for the animals, says Luiz Bermudez, a microbiologist at Oregon State University, and one of the researchers on the study.
“It’s stressful even if we humans get in an airplane and fly for 14 hours,” he says, “so when a fish gets to a destination, many times the fish presents with a kind of stress-related disease.”
To prevent stocks from going belly-up before they reach their destination, many importers often proactively treat their catch with antibiotics. That, says Bermudez, is a big driver of the antibiotic resistance his team found in the study.