You’ve probably heard of bacteria in fish that can cause food poisoning within a couple of days of eating the contaminated seafood. But there are more reasons to be cautious about the fish you eat. Some can host nasty parasites that can also make you very sick by using you as their new living quarters, destroying tissue, diverting nutrients and leading to secondary infections. And while most of the time the effects are similar to food poisoning, some parasites can migrate to organs, where they wreak havoc.
The fish you catch in your local pond is the most likely source of these pests, but fish sold in American supermarkets can also contain visible parasites. “Processors are looking for evidence of parasites. Some even have machines that pull them out,” says Christina Mireles DeWitt, the director of seafood research at the Oregon State University Seafood Research and Education Center. Those methods aren’t always foolproof though. Here are three types of fish parasites you should know about and watch for, along with tips to ensure your catch is safe to eat.