While South America has two Osteoglossum arowanas (the Silver arowana and the Black arowana), and Asia and Australasia have three Scleropages, Africa has a single species — Heterotis niloticus.
Unlike all the others, which are surface-feeding predators, the African arowana is not. It was once considered to be a filter-feeding fish, but recent studies have actually shown that it’s an insectivore, omnivore and detritivore — feeding on small particles of anything that tickles its fancy.
The feeding mode it uses varies according to its age and what habitat it is living in. Little ones, measuring 10-20cm/4-8” long, shift from feeding on small aquatic invertebrates, such as Daphnia, to seeds and detritus.
When they’re found in lakes, they start feeding on detritus when they hit 30-40cm/12-16” long, but when they’re found in rivers they don’t become detritivorous until they’re nearly 0.6m/2’ in length.
They’re rarely kept in the aquarium and have a reputation for being difficult to feed. I’ve tried to rear 3cm/1.1” juveniles before and been wholly unsuccessful.
They also tend to arrive from Africa in a somewhat emaciated state and often riddled with parasites. They’re challenging fish and for that reason are best avoided. There are some little ones on sale in the UK for around £120 apiece.
This item was first published in the September 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.