An arowana is a ten-to-fifteen-year commitment to a fish that will outgrow almost every tank sold in a pet store. We would rather talk you out of one now than take it back at eighteen inches. If you are in, here is what actually matters.
Tank size is the whole decision
A silver arowana reaches two to three feet and does it quickly — most of that growth happens in the first two years. Footprint matters more than volume, because these are surface-oriented fish that need room to turn without hitting glass: width and length, not height. A six-foot tank is a realistic long-term minimum for a silver, and a juvenile in a four-foot tank is a temporary arrangement with a deadline attached. Jardini and other Australian species stay smaller but are considerably more aggressive.
Keep a lid on it, weighted. Arowana jump hard, and it is the single most common way they are lost.
Drop eye
Drop eye — where one or both eyes rotate permanently downward — is the condition arowana keepers worry about most, and it is largely preventable. It is associated with fish that spend their time looking downward: tanks with viewing panels only at the front, food that sinks, and bright overhead lighting that pushes the fish low. Feeding at the surface, floating something on the water to give the fish a reason to look up, and not lighting the tank harshly all help. Once it has set in it does not reverse on its own.
Feeding without ruining the fish
A varied diet on a sane schedule. Juveniles eat more often than adults; an adult arowana does not need feeding every day and is healthier for not being overfed. Avoid an all-feeder-fish diet — it is the classic route to fatty liver disease and it imports parasites. Quality pellets, insects and shrimp give better results and less risk.
We write more about arowana keeping at Arowana.Co, our arowana-specific site.
