Silver Arowana Fish Species Profile

The silver arowana is a large freshwater fish that can be traced back to the Cretaceous Period in prehistoric times. These carnivorous fish have long bodies with large scales and two barbels on the lower jaw. The silver arowana can be a challenge to care for and is not recommended for beginners. Here's what you need to know if you're considering keeping a silver arowana.

Origin and Distribution

The Osteoglossidae family of freshwater fish are members of the ancient ray-finned fishes class, the Actinopterygii. There are eight species in four genera in the family Osteoglossidae, originating from South America (Osteoglossum bicirrhosum, O. ferreirai, and Arapaima gigas), Africa (Heterotis niloticus), Asia (Scleropages formosus and S. inscriptus) and Australia (S. jardinii and S. leichardti) . The Silver Arowana (Osteoglossum bicirrhosum) diverged from the Asian and Australian species during the late Jurassic or early Cretaceous period.

In the pet trade, 10 varieties of arowana are classified by their coloration and origin. In the United States, Asian Arowanas of the species Scleropages formosus (Asian bonytongue or Green Arowana) and Sclerophages inscriptus (Myanmar bonytongue or Scripted Arowana) are listed as endangered CITES level I, requiring a special permit to keep them, as they are threatened with extinction in their native habitats, although they are bred in captivity in Asia and often kept as aquarium pets there. Silver arowanas from South America are not endangered and are commonly sold in the United States as pet fish. Some states do not allow the importation of Arowanas due to its potential threat to native species if it were to be released into warm waters.

Colors and Markings

The various Arowana varieties are commonly classified by their origin and coloration. The common Silver Arowana is a pale silver to gold. Juveniles may have a blue tint and a yellow-orange bar along their side. Other young arowanas may be tinted red or green, depending on their species. Some arowanas can be very expensive pet fish. There are reports of some color varieties of the Asian arowanas selling for over $100,000 per fish.

All arowanas have very large scales with a pair of barbels on their lower jaw. The dorsal and anal fins are almost fused with the tail, giving the fish a streamlined appearance.

Tankmates

No matter what species, arowanas are mostly kept in aquariums as solitary fish. Unless you have a very large aquarium and are planning on breeding arowana, only one fish is recommended. Since they are predators, they will eat any tankmates that will fit into their mouth!

Unfortunately, some arowanas are very picky eaters and refuse to eat anything other than live feeds. Try to avoid this if you can. Keep in mind that any live fish or invertebrates entering the aquarium should be quarantined prior to being fed to your fish to prevent the introduction of pathogens into your aquarium. If your arowana decides not to eat the live food at that time, you may need to consider removing those feeder fish to be housed in another aquarium until a future feeding time.

Arowana Habitat and Care

Arowanas can grow exceptionally large, even though they start deceptively small. You will require at least 300 gallons of water per fish. It is recommended to go bigger if you can and make sure you have a solid aquarium lid, as arowanas actively jump.

In the wild, arowanas are known to leap out of water to capture prey on overhanging branches, a behavior triggered by stimuli such as bright lights or reflections. To prevent unplanned escapes, owners should opt for wider, shallower tanks, which reduce the momentum arowanas gain when swimming towards the surface. Some owners will place a raised collar of plexiglass or netting around the top of their tank with a side door to access the water surface. This will allow your fish to hunt above the water surface naturally while not being able to fly out of the aquarium.

Keep your arowana tank free of obstructions. They are quick to charge their food and may be hindered by numerous decor items. Do not expect live plants to do well in arowana tanks without fertilizer supplementation, since there is only one fish in a large volume of water, unable to produce adequate levels of nitrate. Arowanas may also uproot the plant and up turn ornaments in the aquarium.

Droopy Eye

A common complaint occurring with arowanas is a "droopy eye." This occurs when an arowana has to look down on prey from above while hunting when feeding on fish or sinking food, rather than from below, like their wild counterparts that eat insects off branches above the water. Arowanas are surface sight hunters, so without anything to hunt above the surface, their eyes start to drift downwards. Placing a branch above the water that live food such as crickets can crawl on for the fish to reach up to eat will mimic their natural feeding method.

Many hobbyists attempt to surgically correct droopy eye by removing the retrobulbar fat pad around the dorsal aspect of the eye. Often, these surgeries are only a temporary fix, since your fish will continue to hunt food that is below them, now less successfully. Instead, give your fish something floating on the surface that catches their interest. Frozen food items or floating pellets coated in oil to give them a more reflective surface are some good ideas. Remember, they might try to jump for whatever is on the surface!

Arowana Diet and Feeding

Arowanas are carnivorous fish. Their wild counterparts are known for grabbing prey off the surface of the water or on branches above the water, a hard lifestyle to replicate in an artificial environment. If possible, allow your fish to hunt their meals at the surface.

It's best to feed your arowana a floating pelleted diet, with meaty supplements, such as krill and shrimp. Do not introduce live feeds if your fish is willing to eat a pelleted diet. Many hobbyists have made this mistake and the fish will refuse to go back to the pelleted diet. It may be "fun" or "natural" for your fish to hunt wild prey, but feeder fish could potentially bring in disease and is certainly not a fun experience for the intended prey.

Gender Differences

There are no external differences between male and female arowanas. This is one of the biggest challenges when attempting to breed these fish. It is thought that the male's mouth might be slightly larger between fish of the same age and size, but this has not been verified.

Breeding the Arowana

Arowanas are mouth brooding fish, wherein the male will fertilize the eggs as the female lays them, and then carry the eggs in his mouth. During this time, the males will not eat. The eggs will hatch in about a week, and then the male will carry the fry in his mouth for another 7-8 weeks until the fry are able to eat and live on their own.

More Pet Fish Species and Further Research

If you are interested in other unique fish species, check out:

• Bristlenose Pleco (Ancistrus Cirrhosus)
• Jewelfish (Hemichromis bimaculatus)
• Texas Cichlid (Herichthys cyanoguttatus)

Check out additional fish breed profiles for more information on other freshwater fish.