There are 4 types of arowana in common aquariums. Those are, South American Arowana (lives in the Amazon river of South American continent), Asian Arowana (Endemic for Asian continent), Australian Arowana and African Arowana. Not only the home land, but also they are different in colors. Arowana further divided into several varieties due to the color. Silver Arowana is the most popular Arowana variety among all the varieties, It is the South American variety.
There are two species in South America, Those are Silver Arowana and Black Arowana. Both species are same on the body shape and size but different in colors. Commonly South American species are thin and elongated. Their anal and dorsal fin are less wider than comparing with others. Silver Arowana is the most popular among those. As the name denotes they have silver colored body. Black Arowana is darker and ash or blackish colored and edges of fins are red or yellow in color.
There are 5 varieties of Asian Arowana in the world. Those are, Cross Back Golden Arowana, Super Red (Chili Red) Arowana, Silver Asian Arowana, Red Tail Golden Arowana and Green Arowana. In addition to the main 5 there are more later introduced varieties in the aquarium fish market. Asian Arowana has more wider body than the previous South American species. In addition to this their dorsal and anal fins are short and more wider. Both dorsal and anal fins have shifted to the back a little. Asian species is expensive. There are 20-26 columns of scab from head to tail. Their scales are more bigger than comparing with others.
Australian Arowana also known as Jardini. Most popular Australian Arowana varieties are Pearl Arowana, Australian Black Arowana (Black Jardini), Gold Jardini Arowana and Red Jardini. Width and sizes of fins of those Australian species also close to the Asian Arowana. There are white or pink dots in scales of Pearl Arowana. Major difference between Asian and Australian species is the number of scales. Australian Arowana has 30-36 columns of scales from head to tail. Size of the scales is smaller than the Asian Arowana.
African Arowana is olive and ash in color. Shape is different comparing with other territory Arowana species. Head is also smaller than other species. Size of the mouth is also less than others. Shapes and sizes of the fins are close to the Asian species.
Commonly all territory species of Arowana grow for 2-3 feet long. But they grow about 4 feet in length in the natural environment. If you care them very much they could be able to live for atleast 15-20 years. Arowana is a pretty calm fish. They slowly moving all over the tank every time. But Arowana is a dangerous hunter. They do not think twice to swallow any little fish because of having a big mouth. Therefore do not put small fish with them. Clown Knife fish, Pacu, Oscars, Jaguar Cichlids, Green Terror Fish, Alligator-Gar, Tinfoil Barb and Giant Gourami can put together with Arowana. They regularly come to the surface of the tank while swimming. They not only hunt creatures inside the water but also outsides. They can jump and catch creatures beyond the water. Therefore some people call them as "Water Monkey". A well grown Arowana can jump about 6 feet high from water. Therefore tanks should be covered on top with a soft net to prevent a damage.
After female lay eggs male take the eggs to his mouth and protect. It also protect juveniles for atleast few days after come out. In the natural environment they catch little fish, insects, worms and any little creature for food. When take them to aquarium fish tank they eat any kind of prepared fish food. And there are special foods prepared for Arowana in the market. Arowana is carnivorous. Therefore it is suitable to give small fish, piece of flesh, prawn, etc as extra foods.
We have to prepare about 6x4 feet tank for a well grown couple of Arowana fish. But keep in small tanks in their small age is not harmful. You have to change the tank according to the size of the fish. Arowana always swim all over the tank. Therefore it is recommended to give them more room to swim normally. They can be ill easily with pollute water. Always use a good filter and change the tank water once in two weeks. Keep the PH level between 6.4 and 6.8 to a well grown, healthy Arowana. Arowana is sensitive to the tank water. Therefore do not change all water at once. If you can change half of tank water once a week, it is recommended. Do not use decorations which take more space of the tank.