Osteoglossum bichirrosum (Silver Arowana)

Asian Arowana (Scleropages formosus, in all its different colours): from East Asia (this fish is ennlisted in CITES, Appendix II). It is highly regarded in Far East, because of a "belief" related to the Chinese Geomacy, the Feng Shui. Its price can reach many (really many) thousands of US dollars! Import and / or Trading of this fish is not allowed, by law, in U.S.A; elsewere is ruled by CITES Convention. This is something that everyone is requested to respect fully!

Australian Arowana (Scleropages jardini/leichtardti): from Australia (where they're known as " Saratoga") they are also higly regarded all over the world. CITES position: Free trade worldwide.

African Arowana (Heteriotis niloticus): from Nile river and its basin, in Africa. CITES position: Free trade worldwide.

Arowana, Aro 

Osteoglossidae 

See above (scientific name). The silver arowana (Osteoglossum bichirrosum) = two barbeled bony tongue) is found in South American rivers (Amazon, Rupununi) and in Guyana.

Osteoglossum: (from Greek ostoun = bone and glossa = tongue) bony tongue; bichirrosum = from Latin bi = two and cirrus = lock of hair, curl).

 In captivity they are reputed to grow up to 3 - 4 feet (100 - 120 cm)

The shape of the mouth (upward) and barbels are characteristic of this fish

There is no sexual dimorphism.

Regardless of the origin of a given specimen some requirements are equal to all: Hot, slow flowing waters of a "calm" river (i.e.: Amazon River), dim light … what I would call a "Jungle environment" (Of course it's not very precise but I feel it gives everybody a general idea !). See also point below (tank).  

7 - 7,5 

26° C (increase to 28° if the fish looks "lazy", refuses to feed and so on)  

Not so intense lightning (the spectrum quality in not so important). Filtration on the contrary, is always too weak! I've been told - upon joining a discussion group of Aro keepers, of fellows keeping one single Aro in a 1000 liters tank using 3 fluid filters units, "driven" by a powerhead pump, in a row; plus a canister filter (big enough to service, alone, the whole tank ) working on his own. They're, also, quite fussy on sudden environment (water condition and so on) changes and do need a well oxygenated water to get on well. Air pump(s) is a must to keep oxygen level high (I had, in my tank, one "strong" air pump but, sad to say, a bit noisy) …Water changes can reach 25% of the total water volume on alternate days.  

They're (mostly the Australian species) aggressive fishes and - all of them - ferocious eaters. They use to feed, in wild, on fishes, big insects, frogs, lizards and also small birds (to catch them an Aro can jump over one meter outside the water!). In a tank live crickets are used as "candy" (in Rome: 1 live cricket = ¼ of a U.S. Dollar!), and feed also on chopped shrimps, squids, and/or (live) goldfish, guppies, Betta splendens, and for bigger specimens, also mice!!! Once moderately grown they' ll refuse pellet food (mine was used to …). Feeding such a fish is quite costly!  

Incompatible with anything that will fit in its mouth, or can be seen as food. It is recommended to keep Australian species are kept in a tank of their own due to their solitary and aggressive nature.  

They're aggressive and territorial towards fellows of the same genus. So an Aro has to be kept alone or in a group of 6 - 10 (!!!) specimens. I do wish you luck should you decide to take this option. Arowanas will swallow anything that will fit their huge mouth, so finding suitable tankmates is not that easy. Big catfishes are suggested as possible tankmates (I personally tried 1 foot long plecos) and good size Red Parrot Cichlids and/or freshwater Stingrays (I have no experience with either of them). Those, and others, may be suitable tankmates for an Arowana but always at your own risk.  

Depending on the type of arowana you have, different tank decoration will be appropriate. Arowanas cruise to find food (so make sure, particularly for youngsters, to keep them in still waters so you can observe the “barbells on the surface” behaviour. Arowanas don’t hide so cover places are not a must. South American arowanas will enjoy planted tanks while Australian arowanas are reputed to object to them.

That's the real point! I've raised, when asked by my lfs, a Silver Arowana for 10 months, just to allow him (assuming that this particular fish was a male!) to grow big enough to share a 2000 Lts (530 gals!) tank with the "monsters" already populating it: 3 Oscars (Astronotus ocellatus: over one foot each) and some Tiger Shovelnose catfish (Pseudoplatystoma Sp.; possibly fasciatum: over 2 feet in size). His growth rate has been up to 2,5 cm (1 inch) in a month. When I got him he was still showing the rest of his yolksac while 10 months later it was hitting 30 cm (1 ft) in total length.

Avoid overcrowded conditions as the fish will get stressed. The fish are succeptible to finrot and ich when water conditions deteriorate. More information about my arowana can be found here.  

My arowana, nicknamed "Junior" because of his size upon arrival, was probabaly the most incredible, demanding, fascinating, tiring, satisfying fish I've ever kept.  

Forget it, period! Unless, that is, you're able to re-route the Amazon river in your living room. Industrial Asian Aro breeders - in Singapore - use to house a pair (of S. formosus) in a pond 30 meters (100 feet) in size, depth is not that important but consider fish size, for months (in open air) to induce spawning (Got the idea?). Aros (all) are paternal "mouth-brooders".