Love gorging on fish, but often find it difficult to buy the right one, so you must read on as we decode some secrets to buy that perfect fresh fish. Most of us feel confused with so many choices of fish in the market, but what is even more difficult is to buy the fresh fish and here are some tips to choose the best one!Fresh fish should not smell ‘Fishy’This might come as a surprise, but really fresh fish should not have a fishy smell. Science research explains that the strong smell people think of as fish comes from a chemical called trimethylamine, which builds up when fish starts to go bad after being caught. According to rules from the U.S. Food and Drug Administration (FDA) fresh fish should smell light, clean, and slightly like the ocean or a stream. Not sour.Check the eyesFor fish the eyes are one of the best signs of freshness. Studies on seafood quality show that clear bulging eyes mean the fish is fresh, while cloudy or sunken eyes mean the fish has been around too long. This happens because the eye’s clarity breaks down naturally as enzymes and bacteria work on the fish after it dies.Press the fleshTexture is another sign. Research on fish spoilage has found that fresh fish flesh should feel tight and bounce back quickly when pressed. If your finger leaves a lasting mark, the fish has probably started to lose strength, a process tied to the breakdown of muscle fibers over time.Look at the gillsIf you are buying a fish, look at the gills first. Seafood science research shows that fresh fish gills should be bright red or pink, while brown or gray gills mean the fish is old and has been oxidized. This color change happens as oxygen-carrying parts in the blood break down after the fish is caught.Farmed vs wild-caught fishStudies comparing farmed and wild fish have found differences. Wild-caught fish usually have omega-3 fatty acids because of their natural food. Farmed fish often have total fat, some of which may not be as good depending on how they are raised. Neither choice is automatically bad. Research shows checking labels can help you pick based on your health needs.Mercury levels vary by speciesThis is important for pregnant women and young children. According to FDA and EPA rules, bigger fish like swordfish, king mackerel, and shark have mercury because they are higher on the food chain. Smaller fish like sardines, salmon, and tilapia are low in mercury. Tested well.Frozen fish can be just as good as freshMany people think fresh is always better. Science says that is not always true. Fish that is frozen quickly after being caught often keeps more nutrients than fresh fish that has been in transport and storage for days. Studies on nutrition have found little difference in omega-3 levels between properly frozen fish and fresh fish sold within a day of being caught.