Tench: Tench is not a specie you can commonly find in the United States, but in Eastern Europe, it is pretty common, second only to carp. Trying new types of fish is pretty standard for gourmets, but in this case, we would strongly recommend staying away. The best way to describe the taste of this specie is a mixture of stale water and mud, and when you add a squishy texture, you get a combination that you would probably want to spit out almost instantly. There is no amount of seasoning that could hide the hideous taste of this fish.
Stonefish: There is no one fish that is the most toxic in the ocean, as toxicity can vary greatly depending on the location and species of fish. However, a few fish that are known to be particularly dangerous include the stonefish. Stonefish are a type of wrasse and are found throughout the world’s oceans. They have venomous spines along their dorsal and anal fins, which can be fatal if ingested.
Surströmming: Surströmming, a fermented herring considered to be a famous delicacy in Sweden, is also known as one of the most pungent foods in the world. A newly opened can of surströmming has one of the most putrid food smells in the world, even stronger than similarly fermented fish dishes such as the Korean hongeohoe or Japanese kusaya. And there's one more must-have accompaniment: beer. Herring has been a key part of Swedish culture for centuries. Long ago, Swedish workers were even paid in herring.