In fact, there’s one sure sign you shouldn’t eat a particular piece of fish—and what’s on the packaging could tip you off to the problem. Read on to discover how to spot the issue to keep yourself safe. RELATED: If You’re Over 65, Never Eat This One Kind of Fish, Says CDC. When you’re buying fish, there’s one clear indicator that you should toss a particular package back rather than eating it: ice crystals. While you might imagine that seeing ice on a package of frozen fish is a good sign, indicating that it’s been kept cold, the U.S. Food & Drug Administration (FDA) says otherwise. The authority explains that ice crystals may be an indicator that the fish has spent a prolonged period in storage, meaning it’s not exactly fresh, or that it has thawed and been subsequently refrozen, which could indicate changes in its temperature that could potentially support the growth of dangerous bacteria. For the latest food safety news delivered straight to your inbox, sign up for our daily newsletter! Ice crystals on a fish’s packaging aren’t the only telltale signs that something might be amiss. The FDA recommends steering clear any frozen seafood with torn or open packaging, as well as any packaging with crushed edges. Additionally, you can tell whether or not a frozen fish is a good choice by feeling its flesh—if it’s pliable and doesn’t feel solid, you’re better off avoiding it. Though you may want to avoid any packaged frozen fish that has ice crystals on it, that doesn’t mean ice and fish are always incompatible.ae0fcc31ae342fd3a1346ebb1f342fcb If you’re purchasing fresh fish, the FDA recommends that you only buy products that have been kept on a bed of ice—and, ideally, stored in a case or other enclosed or covered environment—or ones that have been kept refrigerated. While there are plenty of foods you can eyeball to determine their freshness, fish doesn’t number among them. The FDA notes that any fish product that that’s labeled “previously frozen” may have undergone changes that may make its appearance noticeably different from that of a fresh fish. Specifically, a previously frozen fish may have changes in its gill color, texture, bloodlines, and the appearance of its eyes. RELATED: Never Eat Microwaved Food Before Doing This, FDA Warns.