TROPICAL
Please could you give me some information on keeping a silver arowana? I’m aware that these fish get very large and grow fast. I’m considering an aquarium (with a lid) in the region of 2.4mx105cmx90cm deep, built on-site. Would this be large enough or would it need to be wider do you think? There is a concrete floor, so weight should not be an issue. Filtration will be 2x Fluval FX6 filters. Your thoughts would be very welcome.
CLIVE P.
NEALE REPLIES: Silver arowanas, Osteoglossum bicirrhosum, are less commonly traded than the Asian arowana but place the same sort of demands on the fishkeeper, though scaled up somewhat because they can be substantially larger fish. So, while relatively inexpensive, any money saved here is going to be quickly gobbled up by their need for a very large aquarium.
In the wild, a typical adult specimen will reach around 90cm in length, and even in captivity you can still expect 70–80cm. The old rule is that a tank should be at least twice as wide, and six times as long, as the length of the fish being kept, so for a silver arowana of, say 75cm, that’s a tank of 1.5m front to back, and 4.5m from end to end.
People do keep silver arowanas in tanks smaller than that, but what you can get away with, and what’s optimal, are two different things. These are restless fish that live in large rivers and are able to attain enough speed to leap right out of the water and grab their favourite prey (large insects) from overhanging branches. So, while the tank you propose would certainly be suitable for a young specimen, I wouldn’t recommend it in the long term. After all, it wouldn’t be much wider front to back as the length of the fish, and maybe 2-3 times as long as the fish from end to end.
If you can give them the size of tank they need, these fish are otherwise relatively undemanding, providing they don’t have to compete too strongly for food. They often enjoy crickets and things like that but there are specialist
