Another example of a fish that uses camouflage to blend in with its surroundings is the stonefish, a type of scorpionfish. So you see, camouflage is useful because it allows animals such as the gulf flounder and stonefish to avoid predators and to avoid being noticed by animals they are going to eat. Eyes are one of the most noticeable parts of a fish's body. Therefore, many fish have a dark line that runs through the eye to hide this part of the body. Two examples of fish that have a dark line running through their eyes are the reef butterflyfish and the porkfish.
Some fish have false spots, which look like eyes, on their tail or on the rear fins.
These false eyespots can sometimes trick a predator into striking the tail region of the body instead of the head. A fish is more likely to escape a predator if the predator tries to strike its tail, because the fish is swimming away from the predator's mouth not towards it. Poison Some fishes protect themselves from being eaten by injecting the predator with painful venom. The venom is sometimes found in a venom gland on the bottom of a grooved fin spine or, as in the stingray, on a tail spine. Venom can be found in the spines of at least 40 different species of fish.