Silver Arowana – Osteoglossum bicirrhosum

The Silver Arowana, Osteoglossum bicirrhosum, is one of the most iconic freshwater fish in the aquarium hobby. Its long, metallic body, graceful swimming style, and predatory behavior make it a dream species for many advanced aquarists. At the same time, this is a demanding fish that requires a large tank, strong filtration, and responsible planning. In this article, we will look at the biology, care, and aquarium requirements of the Silver Arowana, as well as practical tips for keeping this impressive species healthy and thriving. MB Store offers a wide range of aquariums and aquarium equipment that can help you create a suitable environment for this extraordinary fish.

Origin and Natural Habitat of the Silver Arowana

The Silver Arowana comes from South America, primarily the Amazon, Rupununi, and Essequibo river basins. It inhabits slow-moving or still waters such as flooded forests, backwaters, and marginal zones of large rivers. These environments are typically warm, soft, and slightly acidic, rich in submerged roots, branches, and floating vegetation.

In nature, the Silver Arowana is a surface-oriented predator. Its upturned mouth and elongated body are perfectly adapted to hunting insects, small fish, amphibians, and sometimes even small terrestrial animals that fall into the water. This behavior explains why the fish is such an active jumper and why aquarists must use a very secure tank cover.

Understanding its natural habitat is crucial when designing an aquarium. Recreating similar conditions – open swimming space at the surface, dim lighting, and good water stability – significantly improves the well-being and longevity of the fish.

Appearance and Behavior

The Silver Arowana can reach around 90 cm (sometimes more) in captivity when kept in optimal conditions. Its slender, silver-colored body reflects light beautifully, while large, mirror-like scales give the fish an almost metallic look. The dorsal and anal fins extend along much of the body and merge with the caudal fin, creating a characteristic ribbon-like silhouette.

One of the most recognizable features is the upturned mouth with two barbels (whisker-like appendages) extending from the lower jaw. These barbels help the fish sense movements on the water surface. Arowanas swim in a gliding, almost snake-like manner, which many aquarists find particularly elegant.

Behaviorally, the Silver Arowana is a strong, dominant fish. It prefers the upper levels of the aquarium and patrols the surface constantly. It is usually solitary and may exhibit territorial or aggressive behavior towards conspecifics or similarly shaped fish. Because of its intimidating size and fast movements, it often becomes the center of attention in any large aquarium.

Although it is a predatory species, a properly cared-for Arowana can become quite used to human presence, often recognizing the person who feeds it and coming to the front glass in anticipation. However, it should always be approached with respect: sudden movements, loud noises, or tapping on the glass can startle it and trigger powerful jumps.

Minimum Tank Size and Aquarium Design

One of the most important aspects of keeping a Silver Arowana is providing an appropriately large aquarium. Juveniles are sometimes sold at 10–15 cm, which tempts many aquarists to buy them for smaller tanks. This is a serious mistake. A healthy Arowana grows quickly and needs space for life-long well-being.

For a single adult Silver Arowana, the recommended minimum aquarium size is around 700–900 liters, with a length of at least 200 cm and a width of 70–80 cm. Height is less critical than length and width, but a minimum of 60 cm is recommended to ensure adequate water volume and swimming comfort. The fish must be able to turn around easily and swim in long, unobstructed stretches.

When designing the tank, focus on open surface area. Place larger decorations, roots, or stones more towards the bottom and sides, keeping the center and upper region free. Avoid sharp or rough decorations that could injure the fish if it becomes frightened and dashes around the aquarium.

A secure cover is absolutely essential, and it should be heavy or firmly attached. Silver Arowanas are notorious jumpers and can easily lift light lids or squeeze through small openings. Even a short fall from the tank can be fatal due to internal injuries or damage to the scales and jaw.

MB Store offers large aquariums, sturdy covers, and modular stands that can be adapted to the needs of big fish such as the Silver Arowana. When planning a setup, it is wise to think several years ahead and choose a tank that will be suitable for the adult size of the fish, not just for the juvenile stage.

Water Parameters, Filtration, and Lighting

The Silver Arowana is relatively tolerant of a range of water conditions, but it thrives best in stable, clean water with low levels of organic waste. Because of the fish’s size and appetite, the biological load on the aquarium can be very high, so robust filtration is a necessity.

Recommended water parameters:

• Temperature: 24–28 °C
• pH: 6.0–7.5
• Hardness: soft to moderately hard water

Consistency is more important than chasing extremely specific numbers. Sudden fluctuations in temperature or pH can stress the fish and compromise its immune system.

For a large Arowana tank, use powerful external canister filters or a sump system that can handle high flow and large volumes of biological media. The goal is to quickly convert ammonia and nitrite to relatively less harmful nitrate. Because nitrates can still accumulate and affect health in the long term, regular water changes are essential. Many keepers change 25–40% of the water weekly, depending on stocking and feeding frequency.

MB Store provides a wide range of filters, heaters, and advanced filtration media suitable for large, heavily stocked aquariums. Combining mechanical, biological, and chemical filtration elements can significantly improve water clarity and stability.

Lighting does not need to be extremely intense. In nature, Arowanas inhabit areas with filtered or diffused light. Moderate lighting, possibly with some shaded zones created by floating plants (where possible), helps the fish feel secure. Overly bright light may make them skittish or more prone to sudden stress reactions.

Good surface agitation is beneficial to ensure adequate oxygenation, but avoid creating strong currents directly at the surface where the Arowana spends most of its time. The fish should be able to rest and glide without constantly fighting the current.

Feeding the Silver Arowana

Feeding is one of the most fascinating aspects of keeping a Silver Arowana, but also one where many mistakes are made. In the wild, Arowanas are opportunistic predators, consuming fish, insects, crustaceans, and other small animals. In captivity, it is crucial to provide a balanced diet that supports healthy growth without causing obesity or nutritional deficiencies.

Suitable foods include:

• High-quality floating carnivore pellets formulated for large predators
• Frozen foods such as shrimp, fish fillets, krill, and other marine-origin items
• Occasional live foods from safe, parasite-free sources (in moderation)

Relying exclusively on feeder fish (such as small live fish from random sources) is not recommended. They often carry pathogens and parasites, and their nutritional value is poor. Overuse can also encourage overly aggressive feeding habits and contribute to fatty liver disease.

Young Arowanas should be fed smaller portions two to three times daily, while adults can be fed once or twice per day. It is better to offer moderate amounts and observe the fish’s condition than to overfeed. An overfed Arowana may become sluggish, and excess food quickly deteriorates water quality.

Supplementing the diet with vitamin-rich frozen or prepared foods helps prevent nutritional deficiencies that could lead to deformities or weakened immunity. Many commercial pellet foods designed for large carnivorous fish already contain added vitamins and minerals. MB Store carries specialized fish food for predatory and large species that simplifies the task of providing complete nutrition.

Always remove uneaten food after a reasonable time. This is particularly important in large tanks where leftovers can easily accumulate in corners or behind decorations, putting additional stress on the filtration system.

Tankmates and Community Considerations

The Silver Arowana is not a typical community fish. Its size and predatory nature limit the choice of suitable tankmates, but that does not mean it must be kept alone at all times. With careful planning and a sufficiently large aquarium, some combinations can work well.

General rules for choosing tankmates:

• Avoid any fish that can fit into the Arowana’s mouth – they will almost certainly be eaten.
• Prefer robust, similarly sized or larger species that occupy other water levels (midwater or bottom).
• Avoid fin-nippers or overly aggressive fish that might harass the Arowana.

Suitable companions may include large peaceful or semi-aggressive cichlids, big catfish (such as some Plecos or sturdy bottom dwellers), and larger characins or barbs that are too big to be swallowed. Even then, the specific temperaments of individual fish play a major role, so careful observation is always required.

Keeping multiple Arowanas together is generally discouraged in standard home aquariums. They can be highly territorial and aggressive toward each other, especially in confined spaces. Group keeping is typically only feasible in very large public or custom-built tanks under expert supervision.

When adding new fish, introduce them with the lights dimmed and monitor interactions closely. Rearranging decorations can sometimes help break up established territories and reduce the risk of conflicts. Always have a contingency plan (such as an extra tank or partition) in case the combination does not work out.

Health, Common Problems, and Long-Term Care

With proper care, Silver Arowanas can live 10–15 years or more, becoming true centerpieces of the home aquarium. However, there are some common health issues and care challenges that keepers should be aware of.

Frequent problems include:

• Injuries from jumping – Arowanas may hit the lid or decorations when startled, leading to scale damage, jaw injuries, or even spinal problems.
• Eye issues (such as “drop eye”) – sometimes associated with poor diet, tank design, or genetic predisposition.
• Parasitic infections – often introduced by unquarantined live foods or new tankmates.
• Stress-related illnesses – caused by poor water quality, unstable parameters, or overcrowding.

Preventive care is always easier than treatment. Maintain excellent water quality, perform regular water changes, and test key parameters such as ammonia, nitrite, nitrate, and pH. A high-quality water test kit is a valuable tool for any Arowana keeper, and MB Store carries several options suited to both beginners and advanced aquarists.

Quarantine new fish and avoid introducing wild-caught feeders from unknown sources. If the Arowana shows signs of illness – loss of appetite, clamped fins, unusual swimming behavior, or visible spots and lesions – consult experienced aquarists or an aquatic veterinarian as soon as possible.

Because of their size and strength, handling Silver Arowanas outside the aquarium can be risky both for the fish and the aquarist. Whenever possible, conduct maintenance and interventions inside the tank. If you must move the fish, use large, soft nets and a container rather than attempting to carry it by hand. Keep handling time as short as possible.

Long-term success with this species depends on patience, consistency, and thoughtful planning. Arowanas are not “set and forget” fish – they require ongoing observation and adjustments to filtration, feeding, and tank layout as they grow.

Planning, Equipment, and the Role of MB Store

Before bringing home a Silver Arowana, it is important to evaluate your available space, budget, and long-term commitment. A large custom or standard tank, strong stand, reliable filtration, and high-quality heater are not optional extras – they are the foundation of responsible Arowana keeping.

MB Store offers a broad selection of large aquariums, robust stands, external filters, heaters, and accessories that support stable conditions for big, sensitive fish. You can also find aquarium lighting systems suitable for larger tanks, as well as advanced filtration media that help maintain excellent water quality even under heavy biological load.

When setting up your Arowana aquarium, consider investing in:

• A high-volume tank with strong glass or acrylic and a secure lid.
• Redundant filtration (e.g., two canister filters or a canister plus sump) for safety.
• Reliable, adequately sized heaters or a dual-heater setup for temperature stability.
• Quality test kits to monitor water chemistry regularly.
• Timers for lighting and possibly an automatic feeder if your schedule is irregular.

By combining the right equipment with good husbandry practices, you can provide a healthy, stable environment in which the Silver Arowana will display its full beauty and natural behavior. MB Store can be a long-term partner on this journey, supporting your passion for large and demanding aquarium fish.

Is the Silver Arowana Right for You?

The Silver Arowana is an impressive, charismatic species that can transform a living room into a piece of the Amazon. However, it is not suitable for every aquarist. Its size, strength, and environmental needs demand substantial resources, experience, and dedication.

Before you decide to keep this fish, ask yourself:

• Do I have space for a large, long-term aquarium (700+ liters)?
• Can I afford the necessary equipment and ongoing costs (electricity, water, quality food)?
• Am I prepared for regular maintenance, water changes, and monitoring?
• Do I have a plan for the fish’s adult size, not only for the juvenile stage?

If the answer to these questions is yes, the Silver Arowana can become a fascinating and rewarding companion in your aquarium journey. Its majestic appearance and engaging behavior make every feeding, every glide along the glass, and every quiet evening by the tank a memorable experience.

For aquarists who are not yet ready for such a demanding species, MB Store also offers many other impressive fish and complete aquarium sets suitable for smaller spaces and different levels of experience. This allows you to build up your knowledge and skills gradually before eventually moving on to giants like Osteoglossum bicirrhosum.

FAQ – Silver Arowana in the Aquarium

How big does a Silver Arowana get in a home aquarium?
In a properly sized and well-maintained aquarium, a Silver Arowana usually reaches 70–90 cm, sometimes more. Growth is fastest in the first few years. The final size depends on genetics, diet, and water quality. Because of this potential, it is essential to plan for a very large tank from the beginning and not rely on temporary small setups.

What is the minimum tank size for a Silver Arowana?
For a single adult Silver Arowana, a minimum of around 700–900 liters is recommended, with at least 200 cm in length and 70–80 cm in width. Smaller tanks may temporarily house juveniles but quickly become inadequate. A cramped aquarium leads to stress, deformities, and a higher risk of disease, so long-term planning is crucial.

Can a Silver Arowana live with other fish?
Yes, but tankmates must be chosen carefully. Avoid fish that fit in the Arowana’s mouth, as they will likely be eaten. Suitable companions are large, robust species that inhabit different water levels and are not aggressive fin-nippers. Even then, monitor interactions closely and be prepared to separate fish if aggression or stress becomes evident.

What do Silver Arowanas eat in captivity?
In captivity, Silver Arowanas should be fed high-quality floating carnivore pellets, frozen foods such as shrimp or fish fillets, and occasional safe live foods. A varied diet helps prevent nutritional deficiencies and supports healthy growth. Avoid relying only on cheap feeder fish, as they often carry parasites and can cause health and behavior problems.

Are Silver Arowanas suitable for beginners?
Silver Arowanas are generally not recommended for beginners. Their large adult size, need for strong filtration, sensitive nature, and high equipment costs require prior aquarium experience. Beginners are better off starting with smaller, hardier species and gaining knowledge first. Once you are confident with water chemistry and long-term care, you can consider taking on this demanding fish.