Silver Arowana
Osteoglossum bicirrhosum
Osteoglossidae
About
A ribbon-bodied surface predator from the backwaters, lagoons and flooded forests of the Amazon basin and the Rupununi and Oyapock rivers. Huge mirror-bright scales run the length of a body that ends in fused dorsal, anal and caudal fins, and two short barbels tip the steeply upturned lower jaw. It patrols the top few centimetres of water, taking fish from below, and leaps clear of the surface to snatch insects off overhanging branches - the habit behind its nickname, water monkey. Juveniles sold at 15-30 cm can add most of a metre in two to three years.
Care
Not a tank fish in any normal sense: an adult needs a custom aquarium or indoor pond of roughly 2500 litres and at least 3 m of swimming length, with 4-5 m far better. A heavy, tightly latched lid is mandatory - this is one of the hobby's great jumpers. Give strong but not turbulent flow, high dissolved oxygen, some floating or overhanging cover, and 30-50% weekly water changes; never add one to an immature filter. Keep a single specimen unless the installation is enormous, as rivals fight and a pecking order forms. Poor husbandry, sinking foods and cramped tanks bring on drop-eye, the permanent downward-tilted stare seen in most captive adults.
Diet
Feed at the surface, once daily for juveniles and every second or third day for adults. Small fish take bloodworm, chopped prawn and small earthworms; adults take whole prawns, mussel, fish strips, large earthworms and gut-loaded crickets, with floating dried food in moderation. Avoid beef heart, chicken, feeder fish and mealworms.
Tankmate compatibility
Avoid (271)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
There is no reliable way to sex this species by eye. That is the honest answer, not a gap in our data.
All the methods, with diagramsFrequently asked questions
- What tank size does a Silver Arowana need?
- A Silver Arowana needs an aquarium of at least 2500 litres (660.4 US gallons) with a footprint at least 300 cm (118.1 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Silver Arowana need?
- Silver Arowana does best at 24–30 °C (75.2–86 °F), pH 5–7.5 and a general hardness of 2–15 °dGH.
- Is the Silver Arowana suitable for beginners?
- Silver Arowana is a demanding species best attempted with some experience — it needs stable, closely watched conditions to thrive.