Silver Arowana
Osteoglossum bicirrhosum
Description
The Silver Arowana is a large, predatory freshwater fish known for its sleek, metallic silver body and long, flowing fins. They have an elongated, torpedo-shaped body that can grow quite large, with a distinct, sharp dorsal fin and elongated pectoral fins that give them a unique look. Their large, downward-facing mouth is lined with sharp teeth, and they have two long barbels (whisker-like appendages) near the chin. The Silver Arowana is known for its powerful, graceful swimming style, often seen gliding near the surface of the water with an almost serpentine motion. They are an active, carnivorous species that is highly prized by aquarium hobbyists due to their majestic appearance, though they require a large tank and special care.
Habitat Origin
Native to the Amazon, Orinoco, and other river basins in South America, particularly in Brazil, Peru, and Venezuela. They inhabit slow-moving rivers, floodplains, and backwaters, typically found near the surface of the water, where they prey on smaller fish, insects, and even birds. The Silver Arowana thrives in well-oxygenated water with moderate to slow flow and plenty of submerged structures like roots, plants, and rocks.
Aquarium
Ideal Number in Aquarium: Typically kept alone due to their size and territorial nature.
Favorite Food
Silver Arowanas are carnivores and are known for their hunting abilities. In the wild, they primarily feed on smaller fish, insects, and occasionally small birds. In captivity, they can be fed live or frozen foods such as feeder fish, shrimp, worms, and insects. They may also accept high-quality pellets or specially designed arowana food. It’s important to provide a varied diet to keep them healthy and support their growth.
Behavior:
The Silver Arowana is an active, strong swimmer that prefers to stay near the surface of the water. In the wild, they are known for their acrobatic hunting behavior, where they leap out of the water to catch prey. They are generally peaceful but can be territorial, especially as they grow larger. They may become aggressive toward smaller fish or other species that invade their territory. Despite their predatory nature, they are not typically aggressive toward humans. However, due to their size and temperament, they require a large tank with plenty of space to swim and avoid stress.
Special Care:
Silver Arowanas require a spacious, well-maintained tank with stable water conditions. A tank with a sturdy lid is essential, as Arowanas are known to jump out of the water, especially when startled. The tank should be equipped with strong filtration to maintain water quality, as they are sensitive to poor water conditions. A well-planted tank or one with floating structures can help mimic their natural environment, offering them some cover and a place to rest. Since they are surface dwellers, it is important to keep the water level high enough for them to swim freely. They should not be housed with small fish or species that might be considered prey.
Compatibility with Other Fish:
Silver Arowanas are best kept alone or with large, non-aggressive tankmates that will not fit in their mouths. They are predatory and may attack smaller fish, especially during feeding times. It’s essential to avoid keeping them with slow-moving or small fish, as they may be viewed as food. Larger fish that can defend themselves, such as certain species of catfish or large cichlids, can coexist with a Silver Arowana if the tank is large enough to accommodate both.
Breeding Tank Setup
Breeding Silver Arowanas requires a large, dedicated tank to manage aggression and water quality. A minimum 180-gallon tank (680 liters) is suitable for one breeding pair, while 500 gallons or more is preferred for multiple pairs. Maintain water parameters within pH 6.5–7.5, temperature 26–30°C (79–86°F), and hardness 4–12 dGH. A bare-bottom setup with driftwood or rocks is ideal, and floating plants can mimic their natural habitat. For filtration, use a powerful canister filter or overhead filter, supplemented with a sponge filter for biological support. Use moderate lighting with a 12-hour light/dark cycle to prevent stress.
Conditioning the Breeders
Silver Arowanas are carnivorous, and to stimulate breeding readiness, they require a high-protein, varied diet. Feed them live prey such as feeder fish, shrimp, and crickets, alongside frozen foods like bloodworms and mussels. High-quality carnivorous pellets should also be part of the rotation. Perform weekly 30–40% water changes, and to trigger breeding behavior, simulate a rainy season with a 50–60% water change and a slight temperature increase to 30°C (86°F).
Spawning Behavior
Spawning usually occurs during the early morning, especially after a simulated rainy period. Courtship involves synchronized swimming and circling. A female can lay 100–500 large, sticky eggs, which the male fertilizes and guards. Unlike many species, Silver Arowanas are not strongly prone to cannibalizing their eggs or fry. The male fans the eggs to ensure oxygenation. Monitor the pair closely; if aggression arises, consider separating them.
Fry Hatching & Early Feeding
Eggs hatch within 4–5 days, depending on temperature. The fry initially absorb their yolk sacs before beginning to swim freely. Feed them infusoria or liquid fry food, followed by baby brine shrimp or microworms as they grow. Fry also graze on biofilm and microorganisms in the tank. To protect their health, perform 10–20% water changes daily or every other day, avoid overfeeding, and maintain a stable temperature between 26–30°C.
Breeding Maturity & Care Tips
Silver Arowanas reach breeding maturity at around 3–4 years old. Males are typically leaner with pointed genital papillae, while females appear rounder and fuller, especially when gravid. During breeding, males may display brighter markings. Avoid stress from sudden parameter shifts or tankmate aggression, and ensure high water quality through regular filtration and maintenance. A calm, spacious environment is key to successful spawning and fry development.