Arowana Care Guide: Tank Size, Diet, and Water Quality Essentials

Arowana keeping in India has moved from a niche interest into one of the more serious branches of the monster fish hobby, and for good reason, since a well grown arowana with full colour development is genuinely one of the most striking freshwater fish available to any hobbyist. Arowanas are also unforgiving of shortcuts. Getting tank size, diet, and water quality right from the first week largely decides whether the fish grows into a strong, well coloured adult or struggles with stunted growth, curled fins, and ongoing health issues.

Know What You Are Bringing Home

Most arowanas sold in India fall into a few broad groups, including Asian varieties like the golden crossback and various South American and Australian types that are more widely available to hobbyists. Asian arowana, Scleropages formosus, is listed under CITES Appendix I, which means international trade in wild caught fish is tightly controlled and legal stock has to come from certified captive bred lines with proper documentation. It is worth asking for that paperwork at the time of purchase, both for peace of mind and because it usually signals a fish that was raised properly rather than wild caught and smuggled.

Tank Size Requirements by Growth Stage

Arowanas are surface dwelling predators that grow fast in the first year, so tank length matters far more than tank height. A cramped tank is one of the most common reasons growth stalls early or fins start to curl against the glass.

A tight, weighted lid is not optional with this species. Arowanas are strong jumpers and startle easily, and an open top tank is one of the leading causes of preventable loss in the hobby.

How Fast Arowanas Grow and Why It Matters

A healthy juvenile arowana on a good diet can add close to an inch of length a month during its first year, which catches a lot of first time keepers off guard when they have sized a tank for the fish they brought home rather than the fish it will be in six months. Planning the tank around the adult size from day one avoids a costly mid year upgrade and reduces the stress of repeated rehoming.

Water Quality Essentials

Arowanas tolerate a fairly wide range of water conditions once established, but stability matters more than hitting an exact number. Sudden swings in temperature or pH tend to cause more stress than a parameter sitting slightly outside the ideal range.

A reliable canister filter rated for at least double the tank volume per hour is worth the investment for a fish this size, since arowanas are messy eaters and produce a fair amount of waste. A submersible heater with an external controller keeps temperature swings in check through winter and monsoon months, and keeping a TDS meter and a pH meter on hand makes it easier to catch drift before it becomes a problem, rather than reacting after the fish is already stressed.

Signs Your Water Quality Needs Attention

Clamped fins, a fish that hovers near the bottom instead of patrolling the surface, redness at the gill edges, and reduced appetite are usually the earliest signs that something in the water has drifted. Cloudy eyes and a dull sheen on the scales tend to show up later, once the issue has been building for a while, which is why testing on a schedule matters more than waiting for visible symptoms.

Feeding for Growth and Colour

Arowanas are carnivorous surface feeders in the wild, and their diet in a home tank should reflect that. Juveniles do well on a mix of live and frozen protein sources alongside floating sticks formulated for the species, while adults can shift toward a higher proportion of prepared food once they are established feeders. Colour enhancing supplements are common in the hobby for a reason, since diet has a measurable effect on how vivid the scales and fins turn out as the fish matures, and a consistent feeding routine tends to matter more than any single product.

Choosing the Right Tank Shape and Setup

Length and width matter more than height for a fish that spends most of its time patrolling the upper third of the water column. A long, wide tank with a modest height gives an arowana room to turn without scraping its body against the glass, which is a common cause of scale damage in undersized setups. Open swimming space should take priority over decor, so hardscape and plants work best kept low and along the back and sides rather than scattered through the middle of the tank. A dark coloured background on the rear glass also tends to bring out colour intensity better than a bright or busy one.

Quarantining New Arrivals

A new arowana, whether bought locally or shipped in, should spend two to three weeks in a separate quarantine tank before joining a display setup, even when the fish looks healthy at the point of sale. This gives time to observe feeding response, check for parasites or fungal spots that were not visible at the shop, and let the fish settle from transport stress without the added pressure of a new, larger environment straightaway. Water changes during quarantine should be more frequent and in smaller volumes, since a smaller tank swings on water quality much faster than a large display tank would.

Building a Feeding Schedule

Juveniles under six months benefit from being fed two to three times a day in small portions, since frequent smaller meals support the rapid growth phase without overloading the digestive system or fouling the water as quickly as one large feed would. Once a fish crosses the sub adult stage, this can drop to once or twice a day, with a mix of protein sources rotated through the week rather than relying on a single food item. Overfeeding is more common than underfeeding in this hobby, and leftover food breaking down in the tank is one of the fastest ways to push ammonia and nitrite out of the safe range, so uneaten food should be removed within a few minutes of a feeding session rather than left to be found later.

Common Mistakes First Time Keepers Make

The most frequent mistake is buying too small a tank with the plan to upgrade later, which almost always ends up stunting growth before the upgrade happens. The second is skipping a proper lid, which is how most preventable losses happen with this species. The third is treating tankmates casually. Arowanas are territorial and will treat smaller fish as food, so anything sharing the tank needs to be close in size and temperament, and even then, compatibility should be tested carefully rather than assumed.

Substrate and Decor Safety

A large, fast moving predator in a glass box means decor choices matter more here than in a typical community tank. Sharp edged rocks or driftwood placed too close to the swimming path can injure a startled fish that bolts, so anything with a rough or pointed edge is better placed flush against the back glass rather than free standing in open water. A bare bottom or a fine, smooth substrate is generally safer and easier to keep clean than coarse gravel, which can trap uneaten food and waste against a heavy bioload.

Water Changes and Long Term Maintenance

A weekly water change of around 20 to 25 percent keeps nitrate from building up between full filter services, and it is generally safer for a fish this size than large, infrequent changes that shock the system. Using a proper water conditioner during every change neutralises chlorine and chloramine before it reaches the fish. Testing water parameters weekly during the first few months in a new tank helps catch problems early, since arowanas can mask stress until it has already become serious.

Arowana keeping rewards patience more than almost any other fish in the monster fish hobby. A tank sized correctly from the start, water parameters kept stable rather than perfect, and a feeding routine built around growth and colour together tend to produce a fish that holds its condition for years rather than one that plateaus early and never quite gets there.