A lot of people like watching and studying fish. They like to study the different traits that fish display. Some types of fish are aggressive, while others become prey to these aggressive types. If you are going scuba diving, then it is important for you to know the aggressive ones from the others. Some people choose to keep different types of fish at home as a hobby, either because they like them or because the fish enhance the beauty of the place. On the other hand, some people have an aquarium to study fish. Whatever be the reason, it is natural that an owner will want to know which fish are aggressive in nature. This list will help in deciding which ones to keep. Aggressive Fish Species Aquariums which are home to different species of fish are known as community aquariums. On the other hand, those which have just one species are known as single fish tanks. If they have fish of the same variety, then they are known as single species fish tanks. Barbs (Cyprinidae) Barbs belong to the list of top 10 aggressive fish. The ones that are most commonly seen are tiger barbs, rosy barbs, cherry barbs, and gold barbs. Of these, gold barbs are the least aggressive. If there are fish of other species in the aquarium, then you may want to consider your decision of keeping these fish along with the others. Giant Snakehead (Channa micropeltes) These are said to be their own predators. They are known to be strong, hardy, and extremely aggressive. One of the qualities of these fish is that they are voracious eaters. Zebra Tilapia (Heterotilapia buttikoferi) These fish are basically yellow or white with black stripes, which is how they get their name. They are native to west Africa, Liberia in particular. They mainly live in rivers and streams, usually near the coast. They are known to be very reactive to movements outside the aquarium and try to attack through the glass. They are recommended to be kept in a species tank and not mixed with other fish. Red Belly Piranha (Pygocentrus nattereri) These fish are natives to the rivers of South America and are known to be very notorious. Live food is their staple diet. If they are very hungry or agitated, they can also eat a finger dipped into the water. Tigerfish (Hydrocynus vittatus) These fish are native to Africa. They are found in many rivers and lakes and are popular as fishing game. They have silver-colored bodies. They are extremely aggressive predators. They have razor-sharp interlocking teeth just like the piranhas, although these belong to a different family. They prefer hunting in groups. These are the first ever fish on record to have attacked and caught birds that were in flight. Jack Dempsey (Rocio octofasciata) These fish are native to Guatemala and Honduras. They are known to be destructive in the aquarium. Hence, it is better not to keep them with other fish. They prefer to live in hiding places. Tangs (Acanthuridae) Tangs are also known as surgeon fish or doctor fish. They have small scales on their bodies. Their spine often looks like a scalpel. The spine is used both in aggression as well as for defense. If you want to have them as pets, you will have to make sure that they have sufficient hiding places and a lot of area where they can swim around. Red-Tailed Black Shark (Epalzeorhynchos bicolor) Although these fish derive their name due to their shark-like appearance, they normally feed on plant life and are commonly seen as aquarium fish. They sport a velvety-black and bright-orange tail. They may grow up to six inches, but need a lot of space. Although known to be aggressive chasers, they rarely tend to bite other fish. However, it also depends on the individual fish. It might be calm or aggressive. This species is said to be intolerant of other sharks. Giant Danio (Devario aequipinnatus) These fish come from the southern Asian region. They are silvery-blue in color. They can grow up to four inches in length, but have a narrow, slender body. They are very active species and like to school. Their size and activity level may bring out a lot of aggression in them, and they can eat other fish in the tank. They are better kept in a species tank to avoid other fish from being killed. Deciding which is the world's most aggressive fish is rather difficult. There are some which are inherently aggressive, but in some cases, it can go overboard due to other reasons as well. Some of the reasons are illness, change in temperature or season, on reaching maturity, etc. If you notice any of your fish displaying these characteristics, it is better to isolate them till the reason for this behavior is understood.