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If you’ve ever wanted to keep a living dinosaur, the arowana is about as close as the freshwater hobby gets. These fish have existed for over 100 million years, and everything about them feels ancient – the massive scales, the bony tongue, the way they patrol the surface like they own the tank. They’re intelligent, aggressive, and capable of leaping three feet out of the water to snatch insects off tree branches. Keeping one is a serious commitment, but for experienced hobbyists who have the space and budget, few fish are more rewarding.
That said, arowanas are not for beginners. They need tanks of 240 gallons or more, produce heavy waste, and can be difficult to transition off live food. Asian Arowanas are illegal in the United States, but the South American, Australian, and African species are all legal to keep. This guide focuses primarily on the two South American species – the Silver Arowana and the Black Arowana – and covers everything from tank setup and diet to the notorious Drop Eye condition that plagues captive specimens.
Quick Overview
| Attribute | Details |
|---|---|
| Common Names | Arowana, Dragon Fish, Monkey Fish, Bony Tongue |
| Scientific Names | Osteoglossum bicirrhosum (Silver), Osteoglossum ferreirai (Black) |
| Family | Osteoglossidae |
| Origin | South America (Amazon basin, Rio Negro, Orinoco, Essequibo) |
| Adult Size | 30-36 in (75-90 cm) in captivity; up to 48 in (120 cm) in the wild |
| Growth Rate | Up to 2 inches per month in the first year |
| Lifespan | 10-20 years in captivity (wild specimens estimated at 20-40+ years) |
| Tank Size | 240+ gallons (minimum 8 ft long, 2 ft wide, 2 ft deep) |
| Temperature | 75-82°F (24-28°C) |
| pH | 6.0-7.0 |
| KH | 1-8 dKH |
| Temperament | Semi-aggressive, predatory, territorial |
| Diet | Carnivore/Insectivore (live, frozen, pellets) |
| Care Level | Difficult |
Legality: Which Arowanas Can You Keep?
Before anything else, you need to know the legal landscape. All Asian Arowana species (Scleropages formosus and its color variants – Super Red, Crossback Golden, Red Tail Golden, Green) are listed under CITES Appendix I. It is illegal to import, sell, transport, or keep Asian Arowanas in the United States and many other countries. Violations carry serious federal penalties. If someone offers you a “Red Arowana” or “Golden Arowana” in the U.S., walk away.
The two South American species – the Silver Arowana (Osteoglossum bicirrhosum) and the Black Arowana (Osteoglossum ferreirai) – are legal in most U.S. states. The Australian Arowana (Jardini, Scleropages jardinii) and the Leichardti (Scleropages leichardti) are also legal but less commonly available. African Arowanas (Heterotis niloticus) are occasionally seen but behave very differently from the other species and are not covered in this guide. For a deeper look at the legal issues, see our article on why Asian Arowana are illegal.
Types of Arowanas
Understanding the different arowana species matters because care requirements, size, temperament, and price vary significantly between them. Here’s a comparison of the species you’re most likely to encounter:
| Species | Max Size (Captivity) | Temperament | Price Range | U.S. Legal? |
|---|---|---|---|---|
| Silver Arowana | 36 in | Semi-aggressive, skittish | $30-$200+ | Yes |
| Black Arowana | 30 in | Less aggressive, calmer | $100-$500+ | Yes |
| Jardini Arowana | 24 in | Highly aggressive | $100-$400+ | Yes |
| Asian Arowana (all varieties) | 24-36 in | Varies by variety | $300-$300,000+ | No – Illegal |
| African Arowana | 36 in | Mild, filter feeder | $30-$80 | Yes |
For most hobbyists in the United States, the Silver Arowana is the default choice. It’s the most available, the least expensive, and the largest of all arowana species. The Black Arowana is a better option for keepers who want a slightly smaller, calmer fish with stunning juvenile coloration – young Black Arowanas have vivid yellow-orange banding that gradually fades to a dark, metallic sheen as they mature. The Jardini is the most aggressive of the legal species and generally the hardest to keep with tank mates.
Arowana Appearance
Arowanas have a long, blade-like body with a flat back and a mouth positioned at the very top of the head – built for surface feeding. Two dark, sensitive barbels extend from the lower jaw and function as sensory organs, detecting movement and vibration on the water’s surface. The body is covered in large, heavy scales that catch light and give the fish a metallic, almost armored appearance.
The Silver Arowana is exactly what the name suggests – a shimmering silver body that can take on blue, green, or pinkish iridescence depending on the light and the fish’s mood. Their dorsal and anal fins are elongated and run along most of the body, giving them a distinctive ribbon-like silhouette when swimming. The Black Arowana starts life as one of the most visually striking juveniles in the hobby, with jet-black bodies edged in bright yellow-orange. As they mature, this vivid contrast fades to a uniform dark coloration with a coppery or bronze metallic sheen.
Size and Growth Rate
Juvenile arowanas are typically sold at 2-7 inches, but don’t let that small size fool you. These fish grow up to 2 inches per month during their first year, meaning a 4-inch juvenile can be over a foot long within six months. Silver Arowanas reach 30-36 inches in captivity (up to 48 inches in the wild), while Black Arowanas top out slightly smaller at around 30 inches. A full-grown Silver can weigh over 10 pounds. Growth slows significantly after the first 18-24 months, but they continue filling out in girth and weight for years.
Arowana Tank Setup
Tank Size
The minimum tank size for an adult arowana is 240 gallons, and the dimensions matter as much as the volume. You need at least 8 feet of length and 2 feet of width so the fish can turn around comfortably. Juveniles under 8 inches can start in a 60-75 gallon tank, and a 125-gallon or 150-gallon works well as a grow-out tank for fish up to about 12 inches. Just keep in mind how fast they grow – at roughly 2 inches per month, you’ll be upgrading sooner than you think. Many experienced keepers use custom-built tanks or indoor ponds ranging from 300-500 gallons to give their arowana adequate space long-term.
A heavy, secure lid is absolutely essential. Arowanas are powerful jumpers – in the wild, they launch themselves several feet out of the water to grab insects off branches. In captivity, they jump when startled, when the tank feels too small, or sometimes for no obvious reason. The lid should be locked or weighted down. Even a strong arowana can push aside an unsecured glass top. Use a lid with small gaps rather than a completely open design, and keep in mind that a startled arowana slamming into the lid can injure its barbels, jaw, or scales.
Water Conditions
Arowanas come from warm, slightly acidic, soft water in South American flood plains. Replicating these conditions in your tank is important, especially for reducing stress and preventing disease.
| Parameter | Recommended Range |
|---|---|
| Temperature | 75-82°F (24-28°C) |
| pH | 6.0-7.0 |
| KH | 1-8 dKH |
| Ammonia / Nitrite | 0 ppm (any reading is dangerous) |
| Nitrate | Below 20 ppm (they are very nitrate-sensitive) |
| Water Flow | Moderate to strong (mimics river current) |
Arowanas are more sensitive to nitrate buildup than most large predatory fish. Even nitrate levels that an Oscar or bichir would tolerate without issue can cause appetite loss, stress, and disease susceptibility in an arowana. Test your water at least weekly with a reliable kit, and don’t let nitrates creep above 20 ppm.
Filtration
Heavy filtration is non-negotiable. Arowanas are messy carnivores that produce significant waste relative to their size, and live food remnants decompose rapidly. You need filtration rated for at least 2x your tank volume. For a 240-gallon setup, that means targeting 800+ GPH of total filtration capacity. Many serious arowana keepers run a sump system, and some pair a large canister filter with a sump for redundancy. If you’re using canisters alone, running two is strongly recommended. Check our guide to the best filters for large aquariums for specific recommendations.
Water changes need to be frequent and substantial – 25-30% twice per week is ideal for arowana tanks, especially if you’re feeding live food. Many keepers find that once-a-week changes aren’t enough to keep nitrates in check with the bioload an adult arowana produces.
Substrate and Decorations
There are two schools of thought on substrate for arowana tanks. Some keepers prefer bare-bottom setups because they’re easier to clean and don’t trap uneaten food. Others use sand or fine gravel, which looks more natural and may help reduce stress. If you go with a substrate, use a dark, matte material rather than a bright or reflective one – there’s evidence in the arowana-keeping community that reflective tank bottoms may contribute to Drop Eye syndrome (more on that below).
Decorations should be minimal and smooth. Arowanas are surface dwellers that need long, unobstructed swimming lanes. Large driftwood pieces and smooth rocks can provide some visual barriers without cluttering the space. Avoid anything sharp – arowanas are easily startled and can injure their barbels or scales when they bolt. Hardy plants like Java Fern, Anubias, and Amazon Swords work well if firmly attached, and floating plants are especially beneficial because they give the arowana something to look up at, which mimics their natural environment and may help prevent Drop Eye.
Keep lighting subdued. Arowanas are naturally found in tannin-stained, shaded waters. Bright overhead lighting makes them more skittish and reclusive. Place the tank in a low-traffic area away from doors, windows, and televisions. Light sources near the sides of the tank can encourage the fish to fixate downward or sideways rather than looking up, which is another potential contributor to Drop Eye.
Arowana Diet and Feeding
What They Eat in the Wild
In their natural habitat, arowanas are surface-oriented ambush predators. They cruise just below the surface of flood plain waters, using their barbels to detect movement above. During flood season, when water levels rise to meet overhanging branches, arowanas leap from the water to grab insects, spiders, and even small birds and bats from tree limbs. They also eat fish, shrimp, crabs, frogs, and other small animals. This leaping hunting style is where the name “Monkey Fish” comes from.
Feeding in Captivity
Transitioning an arowana onto prepared foods is one of the biggest challenges new owners face. Wild-caught specimens and many juveniles are conditioned to eat only live prey, and some adults will stubbornly refuse anything that isn’t alive. The key is starting the transition early – the younger the fish, the easier it is to train onto pellets. If you buy a juvenile that’s already eating pellets from the seller, you’re in a much better position than starting with a wild-caught adult.
| Food Type | Best Options | Notes |
|---|---|---|
| Pellets (ideal staple) | Hikari Carnisticks, Hikari Massivore Delite, NorthFin Carnivore | Balanced nutrition, lowest disease risk. Use floating pellets to encourage natural upward-looking feeding behavior. |
| Frozen foods | Shrimp, krill, silversides, smelt | Good for variety and supplementation. Feed 2-3 times per week alongside pellets. |
| Live foods | Crickets, mealworms, earthworms, ghost shrimp | Stimulates natural hunting behavior but carries parasite and disease risk. Quarantine all live food. Insects are safer than feeder fish. |
| Avoid | Goldfish feeders, fatty meats | Goldfish are nutritionally poor and high in fat. A diet heavy in fatty feeder fish is linked to Drop Eye and liver problems. |
Hikari Carnisticks are one of the most widely used floating pellets for arowanas. They stay at the surface, which encourages the natural upward-feeding posture these fish are built for. The floating design also means uneaten pellets are easy to spot and remove before they sink and foul the water. For larger adults, Hikari Massivore Delite is a denser sinking pellet that provides heavier nutrition – though sinking food means the arowana looks downward to eat, so it’s best used as a supplement rather than the primary food.
Feeding Schedule
Feed juveniles (under 12 inches) 2-3 times daily with portions they can consume in 1-2 minutes. Adults do best with one feeding per day or every other day. Arowanas are messy eaters, so remove uneaten food immediately. Their high-protein waste breaks down fast and spikes ammonia if your filtration can’t keep up. Keeping an arowana well-fed also reduces the urge to jump – a hungry arowana is a jumping arowana.
Arowana Tank Mates
Behavior and Temperament
Arowanas are predators that will eat anything small enough to fit in their mouth, and their mouth is deceptively large. Anything under 6 inches is at risk. They’re also territorial and can be aggressive toward newcomers, especially other surface-dwelling fish that invade their patrol zone. That said, they’re not mindlessly violent – an established arowana will generally ignore tank mates that are too large to eat and that stay out of the top third of the water column.
Silver Arowanas are the most skittish of the commonly kept species. They spook easily and are the most likely to injure themselves by crashing into the lid or tank walls. Black Arowanas tend to be calmer overall. Jardini Arowanas are the most aggressive and the hardest to keep with other fish – they’ve been known to attack tank mates well above their weight class.
A useful strategy is to introduce the arowana to the tank first and let it establish territory before adding other fish. This reduces aggression compared to adding an arowana into a tank where other fish are already settled.
Compatible Tank Mates
| Tank Mate | Compatibility | Notes |
|---|---|---|
| Dinosaur Bichir | Good | Bottom-dwelling, armored, stays out of the arowana’s patrol zone. One of the safest pairings. |
| Datnoids | Good | Natural companions in the wild. Similar temperament, different water column zone. Requires 300+ gallons together. |
| Peacock Bass | Good | Active midwater predators that match arowana size. Both species tend to establish and respect territories. |
| Large Catfish (Redtail, Synodontis) | Good | Bottom dwellers that stay out of the way. Must be large enough not to be swallowed. Plecos also work well and help with algae. |
| Clown Loach | Good | Keep in groups of 5+. They grow large enough to avoid predation and tend to occupy the bottom zone. |
| Silver Dollars | Caution | Good dither fish when kept in schools of 6+. Must be large adults (4+ inches) or the arowana will eat them. |
| Oscars | Caution | Can work in 300+ gallon tanks. Oscars can be pushy at feeding time. Monitor aggression closely. |
| Blood Parrot Cichlid | Caution | Can work in very large tanks. Their small mouths make them non-threatening, but they may get bullied. |
| Small Community Fish | Avoid | Tetras, barbs, guppies, small cichlids – all will be eaten. |
| Other Arowanas | Avoid | Two arowanas in the same tank almost always ends in serious aggression. Only attempted in 500+ gallon setups by experienced keepers. |
How to Keep Arowanas Healthy
Arowanas are surprisingly sensitive fish for their size. They react to stress, poor water quality, and dietary issues faster than many other large predatory species. The upside is that most health problems are preventable with strong filtration, consistent water changes, and a balanced diet.
Drop Eye Syndrome
Drop Eye is the signature health issue of captive arowanas, and it deserves its own section because it’s so common and so poorly understood. The condition causes one or both eyes to tilt permanently downward, giving the fish a cross-eyed or drooping appearance. It’s not a disease in the traditional sense – it’s a condition caused by a combination of environmental and dietary factors unique to captivity.
The most widely accepted contributing factors are: a high-fat diet (especially goldfish feeders), which causes fat deposits to accumulate behind the eye; tank environments that encourage the fish to look downward rather than up (bare-bottom tanks with reflective surfaces, bottom-dwelling tank mates, sinking food); head trauma from crashing into lids or tank walls; and possibly genetics, particularly in captive-bred Silver Arowanas. Wild-caught arowanas and those kept in open-top ponds rarely develop Drop Eye.
Prevention is far easier than treatment. Feed floating foods rather than sinking pellets as the staple diet. Use a matte, dark substrate instead of a bare reflective bottom. Add floating plants to give the fish something to look up at. Avoid placing the tank near side-mounted light sources (TVs, windows, lamps) that attract the fish’s gaze sideways and downward. Keep the tank lid secure but not overly bright from above. Once Drop Eye is established, it’s extremely difficult to reverse. Some keepers report improvement by moving the fish to an outdoor pond or open-top setup, but advanced cases with fat deposits behind the eye are generally considered permanent without veterinary intervention.
Common Diseases
| Condition | Symptoms | Treatment |
|---|---|---|
| Ich (White Spot) | White spots on body/fins, scratching against objects, clamped fins | Raise temp to 82-84°F gradually. Use ich medication at reduced dose – arowanas are medication-sensitive. Increase aeration during treatment. |
| Fin Rot | Frayed, ragged, or decaying fin edges with discoloration | Usually caused by poor water quality. Aggressive water changes often resolve it. Antibiotics (tetracycline) for advanced bacterial cases. |
| Dropsy | Swollen body, scales protruding outward (pinecone appearance) | Bacterial kidney infection. More common in juveniles. Treat with antibiotics, salt baths, and pristine water quality. Often fatal if caught late. |
| Gill Rot | Discolored or swollen gills, labored breathing, gasping at surface | Caused by fungal infection from poor water conditions. Increase aeration, perform major water changes, and treat with antifungal medication. |
| Cloudy Eye | White or cloudy film over one or both eyes | Often from bacterial infection, vitamin deficiency, or injury. Improve water quality, vary diet, add aquarium salt. Antibiotics for persistent cases. |
| Physical Injury | Damaged barbels, split fins, scale loss, jaw misalignment | Usually from jumping into the lid. Keep water pristine and the fish will heal on its own in most cases. Prevent by securing the lid and minimizing startling. |
Prevention
Almost every arowana health problem traces back to water quality, diet, or stress. Maintain nitrates below 20 ppm with twice-weekly water changes of 25-30%. Feed a varied, low-fat diet built around quality pellets and lean proteins. Quarantine all live food before offering it. Keep the tank in a quiet location with subdued lighting. Avoid sharp decorations, ensure the lid is secure but padded at the edges, and give the fish enough space to swim without feeling restricted.
When treating a sick arowana, always start with reduced medication doses. These fish are more sensitive to chemical treatments than many other large freshwater species. Remove activated carbon from your filter during treatment, and increase aeration to compensate for the oxygen reduction that many medications cause.
Breeding Arowanas
Breeding arowanas in home aquariums is essentially impossible. Even large public aquariums and dedicated fish farms have had extremely limited success. The space requirements alone are a barrier – you’d need a pond-sized environment to even attempt it. Males and females cannot be reliably distinguished by appearance, so deliberate pairing isn’t practical.
Arowanas are mouthbrooders – the male carries fertilized eggs in his mouth for about a month until they hatch. The fry then remain in the male’s mouth for an additional two to three months while they absorb their yolk sacs and develop enough to survive independently. In the rare cases where breeding has occurred in controlled environments, keepers have sometimes extracted the fry from the male’s mouth to increase survival rates. This fascinating reproductive strategy is one more reminder that these fish are genuinely ancient and unique, but it’s not something you should expect to witness in a home setup.
Frequently Asked Questions
How big do arowanas get?
Silver Arowanas typically reach 30-36 inches in captivity and up to 48 inches in the wild. Black Arowanas are slightly smaller, maxing out around 30 inches. They grow up to 2 inches per month during their first year, so a small juvenile will be over a foot long within six months.
How long do arowanas live?
In captivity, arowanas typically live 10-20 years with proper care. Many unfortunately die sooner due to inadequate tank size, poor water quality, or injuries from jumping. Wild arowanas are believed to live significantly longer, with estimates of 20-40 years being common, though some sources suggest even longer for certain species.
What size tank does an arowana need?
Adults need a minimum of 240 gallons with dimensions of at least 8 feet long by 2 feet wide by 2 feet deep. Juveniles do well in a 60-75 gallon grow-out tank, and a 125-150 gallon works for fish up to about 12 inches. Plan to upgrade as they grow – at roughly 2 inches per month, you’ll move through tank sizes faster than you expect.
Are arowanas illegal in the United States?
Asian Arowanas (all varieties including Super Red, Crossback Golden, and Green) are illegal in the U.S. under CITES and the Endangered Species Act. South American species (Silver and Black Arowana), Australian species (Jardini, Leichardti), and African Arowanas are legal in most states. Check your local regulations before purchasing.
What causes Drop Eye in arowanas?
Drop Eye is caused by a combination of factors unique to captivity: high-fat diets (especially goldfish feeders), tank environments that encourage downward gazing, reflective bare-bottom tanks, head trauma from jumping into lids, and possibly genetics. Prevention is far easier than treatment – use floating foods, dark substrate, floating plants, and avoid fatty feeder fish.
Why does my arowana keep jumping?
Arowanas jump for several reasons: the tank is too small, they’re startled by sudden movement or noise, they’re hungry and hunting, or they’re stressed by poor water quality or aggressive tank mates. Make sure the tank is large enough, placed in a quiet location, and that the fish is well-fed. A secure, weighted lid is essential regardless.
Can arowanas live with other fish?
Yes, in tanks of 300+ gallons. The best tank mates are large, semi-aggressive species that occupy different water zones: bichirs and large catfish on the bottom, datnoids and peacock bass in the middle. Avoid anything small enough to fit in the arowana’s mouth and any other surface-dwelling predators.
How much does an arowana cost?
Silver Arowana juveniles typically cost $30-$80, while larger specimens can run $100-$200+. Black Arowanas are more expensive at $100-$500+ depending on size and coloration. Jardini Arowanas fall in the $100-$400 range. Asian Arowanas, where legal, can cost anywhere from $300 to well over $300,000 for rare color varieties – but again, they are illegal in the United States.
Can arowanas survive out of water?
Arowanas can survive briefly out of water by using their swim bladder to breathe air. If your arowana jumps out of the tank, get it back in the water as quickly as possible – don’t assume it’s dead even if it appears motionless on the floor. Many arowanas have been successfully saved after jumping if they’re returned to the tank within a few minutes.
Can arowanas be bred in captivity?
Breeding arowanas in home aquariums is considered virtually impossible. Even professional facilities have had extremely limited success. Males are mouthbrooders that incubate eggs for about a month, with fry remaining in the mouth for another two to three months after hatching. There’s no reliable way to sex arowanas visually, and the specific environmental triggers for spawning are not well understood. Most specimens in the hobby are wild-caught.
Final Thoughts
Arowanas are not casual pets. They require a massive tank, powerful filtration, frequent water changes, a carefully managed diet, and a keeper who understands that these are wild, powerful animals with specific needs. The investment in equipment alone – a 240+ gallon tank, sump or dual canister filtration, heaters, a secure lid – can easily exceed $2,000 before you even buy the fish.
But for experienced hobbyists who are ready for the commitment, few fish offer what an arowana does. They’re intelligent enough to recognize their owner, dramatic enough to leap from the water during feeding, and striking enough to stop anyone who walks into the room. A well-cared-for arowana can be with you for 15-20 years – more companion than decoration.
The biggest mistakes are buying one before the tank is ready, skimping on filtration, and feeding a diet too heavy in fatty feeders. Get those three things right – tank first, filtration strong, diet lean – and your arowana has every chance of thriving for years to come.
Looking for compatible tank mates? Check our care guides for Datnoids, Dinosaur Bichirs, and Peacock Bass – three of the best companions for a large predator community tank.
