Silver Arowana (Osteoglossum bicirrhosum): The Majestic Giant of Freshwater Aquariums

The Silver Arowana, Osteoglossum bicirrhosum, is one of the most iconic freshwater fish in the aquarium hobby. Known for its sleek, metallic body and graceful swimming style, the Silver Arowana is a popular choice for experienced aquarists who have the space and dedication to care for this impressive predator. With its unique upward-facing mouth, the Silver Arowana is a surface feeder and can grow to impressive lengths, making it both a fascinating and challenging species to keep.

Natural Habitat of the Silver Arowana

Silver Arowanas are native to the slow-moving waters of South America, particularly in the Amazon River Basin. They are typically found in floodplains, swamps, and blackwater rivers, where they thrive in warm, oxygen-rich waters. In their natural habitat, Silver Arowanas are opportunistic feeders, preying on a wide variety of animals, including insects, small fish, amphibians, and even birds and small mammals that venture too close to the water’s surface.

Their long, slender bodies are perfectly suited for gliding through the water as they hunt, and their remarkable jumping ability allows them to catch prey above the waterline. This makes them one of the most fascinating surface feeders in the animal kingdom.

Setting Up the Perfect Aquarium for Silver Arowana

Due to their large size and active swimming habits, Silver Arowanas require a spacious tank with the right conditions to ensure they grow healthy and strong. Keeping them in a home aquarium is a significant commitment, and their size alone makes them more suitable for advanced aquarists with experience in handling large, predatory species.

1. Tank Size and Setup

The most important factor in housing a Silver Arowana is tank size. These fish can grow up to 3-4 feet (90-120 cm) in length, so they require a massive aquarium to accommodate their growth. A minimum tank size of 250-300 gallons is recommended for juvenile Arowanas, but as they grow, many owners transition to even larger tanks or indoor ponds.

The tank should be long and wide, as Silver Arowanas prefer horizontal swimming space over vertical height. It's also crucial to have a tightly secured lid or cover, as Arowanas are notorious jumpers and can leap several feet out of the water if startled or when hunting.

In terms of décor, the tank should be relatively simple with plenty of open swimming space. Driftwood and smooth rocks can be used for decoration, but avoid sharp objects that could injure the Arowana. Plants can be added but should be kept to the edges to maintain open water in the center.

2. Water Conditions

Silver Arowanas thrive in clean, warm water with consistent conditions. Given their size and the amount of waste they produce, a strong filtration system is essential to maintain water quality. Regular water changes are also critical to keeping ammonia, nitrites, and nitrates in check.

• Water Temperature: 75-82°F (24-28°C)
• pH: 6.5-7.5
• Water Hardness: 1-8 dGH

Silver Arowanas are sensitive to poor water conditions, so testing the water parameters regularly is important. A canister filter or sump filter with strong mechanical and biological filtration is ideal for maintaining a clean environment.

3. Feeding Your Silver Arowana

In the wild, Silver Arowanas are carnivorous predators that feed on a wide range of prey. In captivity, they should be provided with a high-protein diet that mimics their natural feeding habits. While younger Arowanas can be fed on smaller prey, their diet needs to evolve as they grow.

• Juveniles: Feed live or frozen foods such as bloodworms, brine shrimp, and small fish.
• Adults: Offer larger food items like crickets, mealworms, shrimp, and feeder fish. You can also provide pieces of fish fillet, squid, or other seafood.

While live food can stimulate natural hunting behavior, it’s important to avoid overfeeding with feeder fish, as this can introduce parasites or diseases. Many aquarists supplement live foods with high-quality pellets designed for large carnivorous fish to provide a balanced diet.

4. Behavior and Social Structure

Silver Arowanas are solitary, predatory fish and are best kept alone or with very carefully chosen tank mates. Due to their size and aggressive feeding habits, they are not suitable for community tanks with small or delicate fish. They are known to eat anything that can fit into their mouths, which includes smaller fish and invertebrates.

That said, some aquarists have successfully kept Silver Arowanas with other large, robust species, such as large South American cichlids, Pacu, or Plecos. However, this should only be attempted in very large tanks where each species has enough space to avoid conflict.

Arowanas can also become territorial as they mature, especially in smaller tanks, so it's important to monitor their behavior if kept with other fish.

5. Compatible Tank Mates

Choosing tank mates for a Silver Arowana can be tricky, as their predatory nature limits the options. When selecting tank mates, it’s essential to choose species that are large enough not to be considered prey and robust enough to handle the Arowana’s dominant personality. Some possible tank mates include:

• Large Cichlids (such as Oscar, Green Terror, or Severum)
• Large Catfish (such as Plecos or Redtail Catfish)
• Pacu or Silver Dollars
• Large Bichirs

Avoid housing Silver Arowanas with small fish, as they will likely end up as a meal.

6. Breeding Silver Arowanas

Breeding Silver Arowanas in captivity is extremely rare and difficult due to the fish's size and specific breeding requirements. In the wild, Silver Arowanas are mouthbrooders, meaning the male carries the fertilized eggs in his mouth until they hatch. This breeding behavior requires a large amount of space, and replicating these conditions in a home aquarium is challenging.

Caring for Silver Arowanas: What to Expect

Caring for a Silver Arowana requires significant space, commitment, and resources. These fish can live for over 10 years in captivity, so they are a long-term responsibility. Their size, diet, and specialized care needs mean they are best suited for experienced aquarists who are prepared to provide them with a large, well-maintained environment.

Silver Arowanas are highly intelligent and can recognize their owners, often interacting with them during feeding times. However, their strength and size mean they can sometimes damage aquarium equipment or even injure themselves if they become startled. Regular maintenance and monitoring are crucial to ensuring their health and well-being.

Conclusion

The Silver Arowana (Osteoglossum bicirrhosum) is a stunning, powerful fish that can become the centerpiece of any large aquarium. While they require significant space and specialized care, they reward dedicated aquarists with their majestic appearance and fascinating behavior.

If you’re looking for a visually striking fish with a commanding presence and are prepared for the responsibility of keeping such a large predator, the Silver Arowana could be a perfect choice. However, ensure you have the right tank setup, resources, and knowledge to provide this incredible fish with the environment it needs to thrive.