The silver arowana (Osteoglossum bicirrhosum) stands as one of the most captivating freshwater fish in the aquarium hobby. Known by various names including the water monkey and dragon fish, this prehistoric-looking predator commands attention with its distinctive appearance and fascinating behaviors. Native to the Amazon River basin of South America, the silver arowana has captured the hearts of experienced aquarists worldwide who appreciate its unique characteristics and challenging care requirements.
If you're considering adding a silver arowana to your aquarium or want to improve your existing care routine, this comprehensive guide covers everything from scientific classification to advanced breeding techniques. We'll explore their natural habitat, explain their complex care requirements, and provide practical solutions to common challenges that arise when keeping these magnificent fish. Understanding the silver arowana's needs is essential for providing the proper environment where they can thrive for their potential 10 to 20-year lifespan.
This ancient species, belonging to the Osteoglossidae family, requires dedication and proper planning from aquarists. Their impressive size, reaching up to 3 feet in captivity, combined with their predatory nature and specific environmental needs, makes them suitable primarily for intermediate to advanced fishkeepers. Let's explore what makes the silver arowana such a remarkable species and how to provide optimal care for these living fossils.
Scientific Classification and Taxonomy
The silver arowana belongs to the ancient family Osteoglossidae, commonly known as the bonytongue fishes. This family name derives from the toothed bone on the floor of their mouth (the "tongue") that bites against teeth on the roof of their mouth. The scientific name Osteoglossum bicirrhosum breaks down into "Osteoglossum" meaning "bone tongue" and "bicirrhosum" referring to the two barbels present on their lower jaw.
Within the taxonomic hierarchy, the silver arowana is classified as follows: Kingdom Animalia, Phylum Chordata, Class Actinopterygii (ray-finned fishes), Order Osteoglossiformes, Family Osteoglossidae, Genus Osteoglossum, and Species O. bicirrhosum. This classification places them among some of the most primitive bony fish still in existence today, with fossil records of their ancestors dating back to the Jurassic period, approximately 150 million years ago.
The Osteoglossidae family includes several other notable species such as the Asian arowana (Scleropages formosus), the Australian arowana (Scleropages jardinii and S. leichardti), and the African arowana (Heterotis niloticus). Among these, the silver arowana and its close relative, the black arowana (Osteoglossum ferreirai), are the only representatives found in South America. This geographic distribution provides insight into the ancient connections between continents when they were part of the supercontinent Gondwana.
Physical Characteristics and Identification
The silver arowana possesses a truly distinctive appearance that makes it instantly recognizable among freshwater fish. Their elongated, laterally compressed body is covered with large, metallic silver scales that reflect light beautifully, creating an almost mirror-like appearance. Each scale is remarkably large and distinct, arranged in horizontal rows that accentuate the fish's streamlined form. The body tapers toward the tail, giving them an almost serpentine appearance when swimming.
One of the most striking features is their large, upward-facing mouth that extends well past their eyes. This superior mouth position is perfectly adapted for their surface-feeding lifestyle in the wild. The lower jaw projects beyond the upper jaw, and two prominent barbels extend from the tip of the lower jaw. These barbels, which can reach several inches in length, function as sensory organs that help detect prey and navigate their environment, particularly in murky water conditions.
The dorsal and anal fins are positioned far back on the body, nearly merging with the caudal fin to create a continuous fin margin along the posterior portion of the fish. This fin arrangement, combined with their powerful tail, enables remarkable jumping ability and swift acceleration when pursuing prey. Adult silver arowanas typically reach 24 to 36 inches in captivity, though wild specimens have been recorded exceeding 4 feet in length. Males and females are difficult to distinguish visually, though males may develop a slightly longer and more pronounced lower jaw during breeding season.
Their eyes are proportionally large and positioned high on the head, providing excellent vision both above and below the water surface. This adaptation allows them to spot potential prey items, including insects and small animals on overhanging branches. The silver arowana's scales can display subtle color variations depending on lighting and water conditions, sometimes showing hints of blue, green, or pink iridescence, particularly along the lateral line and near the gill covers.
Natural Habitat and Distribution
Silver arowanas inhabit the vast river systems of tropical South America, with their range extending throughout much of the Amazon River basin. They are found in Brazil, Peru, Colombia, Ecuador, Guyana, and French Guiana, occupying both whitewater and blackwater river systems. These fish prefer slow-moving or still waters, including river margins, floodplain lakes (várzea), oxbow lakes, and flooded forests during the wet season.
In their natural environment, silver arowanas typically inhabit areas with dense overhanging vegetation, which provides both shade and a source of food in the form of insects and small vertebrates that fall into the water. The water in their native habitat is generally soft and acidic, with pH values ranging from 6.0 to 7.0, and temperatures consistently between 75°F and 86°F (24°C to 30°C) throughout the year. The dissolved oxygen levels in these waters can vary significantly, and arowanas have adapted to survive in low-oxygen conditions by gulping air at the surface.
During the Amazon's flood season, which typically occurs from December to May, silver arowanas move into flooded forests where food is abundant. This seasonal flooding creates vast areas of inundated forest canopy where arowanas can access prey items normally out of reach. They have been observed jumping up to 6 feet out of the water to catch insects, small birds, bats, and even small monkeys from low-hanging branches, earning them the nickname "water monkey" or "monkey fish" among local populations.
The ecological role of silver arowanas in their native habitat is that of an apex predator in the surface and mid-water zones. They help control populations of smaller fish, insects, and crustaceans while serving as prey for larger predators such as caimans, river dolphins, and large catfish when they are young. Understanding their natural habitat is crucial for recreating appropriate conditions in captivity and appreciating their behavioral adaptations.
Aquarium Setup and Tank Requirements
Setting up an appropriate aquarium for a silver arowana requires careful planning and significant investment due to their large adult size and active nature. The absolute minimum tank size for a single adult silver arowana is 250 gallons, though 300 to 400 gallons provides a more comfortable environment. The tank dimensions are just as important as volume – a minimum length of 8 feet, width of 3 feet, and height of 2 feet is recommended to allow adequate swimming space and turning radius for these large fish.
Tank security is paramount when keeping silver arowanas due to their notorious jumping ability. A tight-fitting, sturdy lid is absolutely essential, as these fish can generate tremendous force when jumping and have been known to break through flimsy covers. Leave at least 6 inches of space between the water surface and the lid to prevent injuries from jumping. Some aquarists prefer to use weighted glass tops or custom-built canopies with locks to ensure the fish cannot escape.
The filtration system must be robust enough to handle the significant bioload produced by these large predators. A combination of mechanical, biological, and chemical filtration is recommended, with a turnover rate of at least 4-6 times the tank volume per hour. Canister filters, sumps, or a combination of both work well for arowana tanks. Strong water movement should be avoided in the main swimming areas, as arowanas prefer relatively calm water, though good circulation is necessary to maintain water quality.
Substrate choice for arowana tanks is largely aesthetic, as these fish spend most of their time in the middle to upper water columns. Fine sand or smooth gravel works well, though many keepers prefer bare-bottom tanks for easier maintenance. Decorations should be minimal and carefully selected – large pieces of driftwood or smooth rocks can provide visual interest without impeding swimming space. Avoid sharp or rough decorations that could injure the fish if they make sudden movements. Live plants are generally not recommended as arowanas may uproot them, though floating plants like water lettuce or Amazon frogbit can provide shade and help maintain water quality.
Water Parameters and Quality Management
Maintaining optimal water parameters is crucial for the health and longevity of silver arowanas. These fish require tropical temperatures between 75°F and 82°F (24°C to 28°C), with 78°F to 80°F being ideal for most situations. Temperature stability is important, as sudden fluctuations can stress the fish and compromise their immune system. Use a reliable heater rated for your tank size, and consider using two heaters for redundancy in case one fails.
The pH should be maintained between 6.5 and 7.5, with 6.8 to 7.2 being optimal for long-term health. Silver arowanas can adapt to slightly different pH levels, but sudden changes should be avoided. Water hardness should be kept relatively soft to moderate, with general hardness (GH) between 3 and 12 dGH and carbonate hardness (KH) between 2 and 8 dKH. These parameters mimic their natural blackwater and clearwater habitats in South America.
Nitrogen cycle management is critical given the large bioload these fish produce. Ammonia and nitrite levels must be maintained at 0 ppm at all times, as arowanas are sensitive to these toxic compounds. Nitrate levels should be kept below 20 ppm through regular water changes, though lower levels are preferable. Weekly water changes of 25% to 35% are typically necessary, though this may need to be increased based on feeding frequency and bioload.
Regular testing of water parameters using liquid test kits or digital meters is essential for early detection of problems. Keep detailed records of your water parameters to identify trends and potential issues before they become serious. Consider investing in a quality water testing schedule and maintaining it consistently. Some aquarists find success using RO (reverse osmosis) water remineralized to appropriate levels, which provides better control over water chemistry and reduces the introduction of potential contaminants from tap water.
Feeding and Dietary Requirements
Silver arowanas are opportunistic carnivores with a diverse diet in the wild that includes fish, insects, crustaceans, and even small terrestrial animals. In captivity, providing a varied diet is essential for optimal health, growth, and coloration. Juvenile arowanas should be fed 2-3 times daily, while adults can be fed once daily or every other day, depending on the size of meals and the individual fish's metabolism.
Live foods are often preferred by arowanas and can include feeder fish (quarantined and gut-loaded), crickets, mealworms, earthworms, and ghost shrimp. However, feeder fish should be used sparingly due to the risk of disease transmission and nutritional imbalances. When using feeder fish, ensure they are properly quarantined for at least two weeks and fed nutritious foods before offering them to your arowana. Avoid goldfish as feeders due to their high fat content and potential for carrying diseases.
Frozen foods offer a safer and more convenient alternative to live foods. Options include frozen fish (tilapia, salmon, mackerel), krill, prawns, and bloodworms. These should be thawed completely before feeding and any uneaten portions removed promptly to maintain water quality. Cut larger food items into appropriate sizes – pieces should be no larger than the width of the arowana's head to prevent choking.
High-quality pellets formulated specifically for large carnivorous fish can form the staple diet for silver arowanas. Look for pellets with high protein content (at least 40-45%) and quality ingredients like whole fish meal rather than by-products. Some arowanas may be reluctant to accept pellets initially, but persistence and hunger usually overcome this resistance. Floating pellets are preferable as they match the arowana's natural surface-feeding behavior. Supplement pellet feeding with frozen or live foods 2-3 times per week for dietary variety and enrichment.
Behavior and Temperament
Silver arowanas exhibit fascinating behaviors that reflect their predatory nature and evolutionary adaptations. They are generally solitary fish that establish territories within their environment, though they can coexist with appropriate tank mates under the right conditions. These fish are most active during dawn and dusk periods, corresponding to their crepuscular hunting patterns in the wild.
One of the most notable behaviors is their surface-dwelling tendency. Silver arowanas spend most of their time in the upper third of the water column, constantly scanning the surface for potential prey. They often position themselves at a slight upward angle, ready to strike at anything that disturbs the water surface. This behavior is so ingrained that even well-fed captive specimens will investigate any movement above the tank.
The jumping behavior of silver arowanas is legendary among aquarists. In the wild, this ability allows them to catch prey from overhanging branches, but in captivity, it can lead to injuries or escape attempts. Stress, poor water quality, insufficient space, or the presence of perceived threats can trigger jumping behavior. Some individuals are more prone to jumping than others, and this tendency often increases during feeding time or when the tank lid is opened for maintenance.
Intelligence is another remarkable trait of silver arowanas. They quickly learn to recognize their keepers and can be trained to take food from their owner's hand. Many aquarists report that their arowanas display distinct personalities, with some being more aggressive or skittish than others. They also demonstrate problem-solving abilities and can become bored in sparse environments, which may lead to stress-related behaviors like rubbing against tank walls or refusing food. Providing environmental enrichment through varied feeding techniques, occasional rearrangement of decorations, or the addition of appropriate tank mates can help maintain mental stimulation.
Compatible Tank Mates
Selecting appropriate tank mates for silver arowanas requires careful consideration of size, temperament, and habitat preferences. The primary rule is that any tank mate must be too large to fit in the arowana's mouth, as anything that can be swallowed likely will be. Additionally, tank mates should not compete for the same water column space and should be peaceful enough not to harass the arowana.
Large, peaceful bottom-dwelling fish make excellent companions for silver arowanas. Suitable options include large plecos (common pleco, royal pleco, or sailfin pleco), stingrays (if the tank is large enough), and large catfish species like the redtail catfish or tiger shovelnose (in very large systems). These fish occupy different areas of the tank and generally ignore the arowana. Similar to the silver dollar fish care requirements, tank mates should be chosen based on compatible water parameters and peaceful temperament.
Mid-water fish that can coexist with arowanas include large peaceful cichlids such as oscars, severums, or chocolate cichlids, provided they are introduced when both species are young to grow up together. Large characins like silver dollars or pacus can also work in sufficiently large tanks. Some aquarists have success keeping multiple silver arowanas together, though this requires an enormous tank (1000+ gallons) and careful monitoring for aggression, especially during feeding time.
Fish to avoid include aggressive species that may attack the arowana (such as large aggressive cichlids like dovii or red devils), fish with long flowing fins that may trigger the arowana's predatory instincts (like fancy goldfish or angelfish), and any fish small enough to be eaten. Also avoid keeping silver arowanas with other surface-dwelling predators like gars or snakeheads, as competition for space and food will likely lead to conflict. Fast-moving or hyperactive fish that may stress the arowana should also be avoided.
Breeding Silver Arowanas
Breeding silver arowanas in captivity is extremely challenging and rarely achieved in home aquariums due to the massive space requirements and the difficulty in sexing these fish. In their natural habitat, breeding occurs during the flood season when water levels rise and food becomes abundant. Males develop a slightly longer and deeper lower jaw during breeding season, but this difference is subtle and unreliable for sexing outside of breeding condition.
Successful breeding typically requires a pond or tank of at least 2000 gallons with stable water parameters and excellent filtration. The breeding pair must be well-conditioned with high-quality foods and may need environmental triggers such as temperature fluctuations, water level changes, or barometric pressure changes to stimulate spawning behavior. Some commercial breeders use hormone injections to induce spawning, but this requires expertise and is not recommended for hobbyists.
Silver arowanas are mouthbrooders, with the male taking responsibility for incubating the eggs and protecting the fry. After spawning, the female releases 50 to 200 large eggs, which the male fertilizes and then collects in his mouth. The incubation period lasts approximately 50 to 60 days, during which the male does not eat. The fry remain in the male's mouth even after hatching, absorbing their yolk sacs and only venturing out briefly as they grow larger.
Raising arowana fry requires meticulous attention to water quality and appropriate feeding. Newly released fry are already 3 to 4 inches long and can immediately accept small live foods like baby brine shrimp, daphnia, and mosquito larvae. Growth is rapid with proper feeding, and young arowanas can reach 12 inches within their first year. Separating aggressive individuals early is important to prevent cannibalism, which can occur even among siblings.
Common Health Issues and Disease Prevention
Silver arowanas, while generally hardy, are susceptible to several health issues that can be prevented or managed with proper care. Drop eye is one of the most common problems in captive arowanas, where one or both eyes permanently look downward. This condition is thought to result from constantly looking down for food in aquariums, unlike their natural upward-gazing behavior. Prevention includes feeding floating foods, varying feeding locations, and providing overhead stimulation with appropriate lighting or decorations above the tank.
Gill curl or gill cover problems occur when the gill covers grow abnormally, curling outward and exposing the sensitive gill filaments. This condition is often linked to poor water quality, insufficient oxygen levels, or genetic factors. While mild cases may not significantly impact the fish's health, severe gill curl can make breathing difficult and increase susceptibility to infections. Prevention focuses on maintaining excellent water quality and ensuring adequate oxygenation.
Parasitic infections, particularly external parasites like ich (white spot disease) and flukes, can affect arowanas, especially newly imported specimens. Symptoms include white spots, excessive mucus production, flashing against objects, or rapid gill movement. Quarantine all new fish for at least 4 weeks before introducing them to the main tank, and maintain optimal water conditions to boost immune system function. Treatment typically involves gradually raising temperature and using appropriate medications, though arowanas can be sensitive to certain chemicals, so always follow dosing instructions carefully.
Bacterial infections often manifest as fin rot, body ulcers, or cloudy eyes, usually resulting from poor water quality, injuries, or stress. Early detection and treatment are crucial for successful recovery. Maintaining pristine water conditions, avoiding overcrowding, and minimizing stress are the best preventive measures. Nutritional deficiencies can lead to various problems including poor coloration, stunted growth, or bent spine. Providing a varied, high-quality diet supplemented with vitamins ensures proper nutrition. Regular observation of your arowana's behavior, appetite, and appearance allows for early detection of health issues when they are most treatable.
Conservation Status and Ethical Considerations
The silver arowana is currently listed as "Least Concern" by the International Union for Conservation of Nature (IUCN), indicating that wild populations are considered stable. However, this status doesn't mean the species faces no threats. Habitat destruction due to deforestation, dam construction, and pollution in the Amazon basin poses long-term risks to wild populations. Additionally, overfishing for the aquarium trade and as a food source in some regions can impact local populations.
Unlike the Asian arowana, which is listed under CITES Appendix I and heavily restricted in international trade, the silver arowana is not currently protected under international trade regulations. However, some countries within its native range have implemented local regulations governing collection and export. Brazil, for example, has restrictions on the export of wild-caught specimens, though captive-bred fish can be legally exported with proper documentation.
For aquarists, choosing captive-bred silver arowanas over wild-caught specimens is an important ethical consideration. Captive-bred fish are generally hardier, better adapted to aquarium conditions, and less likely to carry diseases or parasites. Supporting responsible breeders helps reduce pressure on wild populations and promotes sustainable practices in the aquarium trade. When purchasing a silver arowana, ask about its origin and look for documentation proving legal importation and captive breeding.
The long-term commitment required for keeping silver arowanas is another ethical consideration. With proper care, these fish can live 10 to 20 years and require increasingly large tanks as they grow. Potential owners must honestly assess their ability to provide appropriate housing and care throughout the fish's entire lifespan. Rehoming large adult arowanas can be extremely difficult, as few facilities or private aquarists have the space to accommodate them. Consider these factors carefully before acquiring a silver arowana to ensure you can provide a permanent, appropriate home.
Tank Maintenance and Long-term Care
Establishing a consistent maintenance routine is essential for the long-term health of silver arowanas. Weekly tasks should include testing water parameters (ammonia, nitrite, nitrate, pH, temperature), performing water changes of 25-35%, cleaning or rinsing mechanical filter media, and removing any uneaten food or debris from the tank. During water changes, use a gravel vacuum to remove waste from the substrate if present, and clean the tank glass to maintain visibility.
Monthly maintenance tasks include deep cleaning filters, checking and calibrating equipment (heaters, thermometers, pH meters), inspecting the tank and stand for any signs of wear or damage, and trimming or replacing any live plants if present. This is also a good time to assess your arowana's growth and consider whether tank upgrades will be needed in the near future. Document your fish's size and any notable changes in behavior or appearance.
Equipment redundancy is important for arowana tanks given the value and longevity of these fish. Keep spare heaters, air pumps, and filter media on hand for emergencies. Consider installing a battery-powered air pump for power outages, and have a plan for maintaining temperature during extended power failures. Some dedicated arowana keepers invest in generator systems or battery backups for critical equipment.
Long-term planning should account for the arowana's growth and changing needs. Young arowanas can start in smaller tanks (75-125 gallons) but will require upgrades as they grow. Plan these transitions carefully to minimize stress, and cycle new tanks thoroughly before moving the fish. As arowanas age, they may become less active and require adjustments to feeding frequency and tank layout. Older specimens may develop age-related health issues requiring more frequent monitoring and potential veterinary care. Building a relationship with an aquatic veterinarian experienced with large fish can be invaluable for addressing health concerns that arise over the years.
Feeding Strategies and Enrichment
Developing effective feeding strategies for silver arowanas goes beyond simply providing food. These intelligent predators benefit from feeding routines that stimulate their natural hunting behaviors while ensuring proper nutrition. Varying feeding times slightly can prevent the fish from becoming too dependent on a rigid schedule, though consistency in frequency is important for digestive health.
Target feeding using feeding tongs or sticks allows for precise food delivery and can help prevent drop eye by encouraging upward viewing. This method also provides an opportunity to interact with your arowana and monitor its health closely. Some aquarists successfully train their arowanas to jump for food (in a controlled manner) by holding food slightly above the water surface, though this should be done carefully to prevent injuries from hitting the tank lid.
Food enrichment techniques include hiding food in floating objects or allowing live prey to swim freely before feeding time, stimulating hunting behavior. Occasional fasting days (once weekly for adults) can help prevent obesity and maintain hunting interest. Some keepers report success with puzzle feeders designed for large fish, though these must be carefully selected to prevent injury.
Monitoring body condition is crucial for adjusting feeding amounts. A healthy arowana should have a streamlined body without a pronounced belly or visible ribs. Overfeeding is a common problem that can lead to fatty liver disease and shortened lifespan. Keep detailed feeding records including type, amount, and the fish's response to different foods. This information becomes valuable for identifying preferences and potential health issues. Similar to guppy fish care, maintaining proper feeding schedules and variety is essential, though the scale and types of food differ significantly.
Advanced Aquascaping for Arowanas
While silver arowanas require open swimming space, thoughtful aquascaping can enhance both the aesthetic appeal and functionality of their habitat. The key is creating an environment that provides visual interest without impeding movement. Large pieces of Malaysian driftwood positioned along the back and sides of the tank can create a natural backdrop while leaving the center open for swimming.
Floating plants serve multiple purposes in arowana tanks. Species like Amazon frogbit, water lettuce, or red root floaters provide shade, help maintain water quality by absorbing nitrates, and create a more natural environment. These plants should be contained to prevent them from covering the entire surface, which could interfere with feeding and gas exchange. Some aquarists use floating plant corrals made from airline tubing to control plant spread.
Background choices can significantly impact the arowana's appearance and behavior. Dark backgrounds tend to intensify the fish's coloration and create a more dramatic display, while lighter backgrounds can make the tank appear larger. Three-dimensional backgrounds that mimic rock faces or root systems can add depth without taking up swimming space. Some keepers report that their arowanas show less stress-related behaviors with naturalistic backgrounds compared to plain colored ones.
Lighting plays a crucial role in both showcasing the arowana's metallic scales and maintaining any live plants. LED lights with adjustable intensity and color temperature allow for customization throughout the day. Many aquarists program sunrise and sunset periods to mimic natural lighting cycles, which can help regulate the fish's circadian rhythm. Proper lighting positioning can minimize shadows that might startle the fish while highlighting their impressive appearance during viewing.
Understanding Arowana Intelligence and Training
Silver arowanas possess remarkable intelligence that sets them apart from many other aquarium fish. They demonstrate clear recognition of individual humans, often showing excitement when their primary caretaker approaches while remaining wary of strangers. This cognitive ability extends to associating specific actions with outcomes, such as recognizing feeding containers or the sound of food preparation.
Training arowanas can enhance the keeping experience and provide mental stimulation for the fish. Simple training can begin with hand-feeding, gradually building trust until the fish comfortably takes food from your fingers. More advanced training might include teaching the fish to swim through hoops, follow a target stick, or respond to visual cues for feeding. These activities should always prioritize the fish's safety and comfort, avoiding any techniques that might cause stress or injury.
Environmental enrichment is crucial for maintaining psychological health in these intelligent fish. Periodic rearrangement of decorations (while maintaining adequate swimming space), introduction of novel objects for investigation, or varying water flow patterns can provide mental stimulation. Some aquarists report success with mirrors placed outside the tank for short periods, though this should be monitored carefully as some individuals may become stressed by their reflection.
Problem-solving opportunities can be incorporated into daily care routines. For example, placing food in different locations or at varying depths encourages exploration and hunting behaviors. Some keepers create simple puzzles using PVC pipes or other aquarium-safe materials that require manipulation to access food rewards. These activities not only provide enrichment but also allow observation of the fish's learning capabilities and individual personality traits.
Dealing with Common Behavioral Issues
Aggression in silver arowanas can manifest in various ways, from attacking tank mates to showing territorial behavior toward their own reflection. Understanding the root causes of aggression is essential for management. Insufficient space is often the primary trigger, as cramped conditions increase stress and territorial behavior. Ensuring adequate tank size and providing visual barriers with decorations can help reduce aggressive incidents.
Refusal to eat is another common issue that concerns many arowana keepers. This can result from stress, illness, poor water quality, or simply boredom with a monotonous diet. New arowanas often refuse food for several days to weeks after introduction to a new environment. Patience is key during this adjustment period, though water quality should be carefully monitored as stress can compromise immune function. Offering a variety of foods and maintaining consistent water parameters usually resolves feeding issues in healthy fish.
Glass surfing or pacing behaviors indicate stress or boredom in arowanas. This repetitive swimming along the tank walls can lead to nose injuries and general wear on the fish's body. Causes include insufficient space, lack of environmental enrichment, poor water quality, or external stressors like excessive activity near the tank. Addressing the underlying cause, whether through tank upgrades, environmental modifications, or relocating the tank to a quieter area, is necessary to resolve this behavior.
Jumping attempts, beyond the natural tendency of the species, can increase due to various stressors. Poor water quality, particularly high ammonia or nitrite levels, often triggers escape attempts. Aggressive tank mates, sudden movements or loud noises near the tank, and inadequate tank dimensions can also increase jumping behavior. Regular water testing, appropriate tank mate selection, and maintaining a calm environment around the tank help minimize this dangerous behavior. Installing a secure, well-fitted lid is non-negotiable for arowana tanks, regardless of the individual fish's jumping tendency.
Regional Variations and Locality Types
While all silver arowanas belong to the same species, subtle variations exist among populations from different regions of South America. These regional differences, though not scientifically classified as subspecies, are recognized by experienced keepers and can affect appearance, maximum size, and behavior. Understanding these variations can help aquarists make informed decisions when selecting their fish.
Colombian silver arowanas are often considered among the most desirable in the trade, typically displaying intense metallic coloration and reaching impressive sizes. These specimens often show stronger silver or platinum coloration with minimal yellow tinting. Brazilian varieties, particularly those from the Rio Negro basin, may display slightly different body proportions and can show more golden or bronze tones in their scales under certain lighting conditions.
Peruvian silver arowanas, especially those from the Ucayali River system, are known for their robust build and excellent appetite in captivity. Some keepers report that Peruvian specimens adapt more quickly to prepared foods and show less skittishness than fish from other regions. However, these observations are largely anecdotal and may be influenced by collection and handling methods rather than true genetic differences.
Wild-caught versus captive-bred specimens also show notable differences. Wild-caught fish often display more intense coloration and natural behaviors but may be more challenging to acclimate to aquarium conditions. They may also carry parasites or diseases and show greater sensitivity to water parameter changes. Captive-bred arowanas, particularly those from established breeding lines, tend to be hardier, more accepting of prepared foods, and better adapted to aquarium life from the start. When possible, choosing captive-bred specimens supports sustainable practices while often providing a better experience for the aquarist.
Frequently Asked Questions
How fast do silver arowanas grow?
Silver arowanas exhibit rapid growth during their first year, potentially reaching 12 to 18 inches with proper feeding and care. Growth rate gradually slows as they mature, with most reaching 24 to 30 inches by age three. Maximum size in captivity typically ranges from 30 to 36 inches, achieved around 5 to 7 years of age. Growth rate depends heavily on tank size, water quality, diet quality, and feeding frequency.
Can silver arowanas live with oscars?
Silver arowanas can successfully coexist with oscars when both species are introduced as juveniles and grow up together. The tank must be large enough (minimum 400 gallons) to provide adequate territory for both species. Monitor interactions carefully, as individual personalities vary, and some combinations may not work despite proper conditions. Ensure both fish receive adequate food during feeding time to prevent competition-related aggression.
Why is my arowana swimming at the bottom of the tank?
Bottom-dwelling behavior is unusual for silver arowanas and often indicates a problem. Possible causes include poor water quality (test immediately for ammonia, nitrite, and nitrate), illness or parasitic infection, stress from aggressive tank mates or environmental changes, or swim bladder issues from overfeeding or constipation. Address water quality issues immediately and observe for other symptoms like loss of appetite or unusual body position.
How often should I feed my adult silver arowana?
Adult silver arowanas should typically be fed once daily or every other day, depending on the individual fish's metabolism and the amount fed per meal. Feeding every other day with larger portions can help maintain water quality while ensuring adequate nutrition. Monitor body condition closely and adjust feeding frequency accordingly. Occasional fasting days (once weekly) can benefit digestive health and maintain hunting interest.
What's the minimum tank size for a juvenile silver arowana?
Juvenile silver arowanas (6-12 inches) can temporarily be housed in 75 to 125-gallon tanks, but rapid growth necessitates planning for upgrades. By the time they reach 18 inches (often within the first year), they need at least 180 gallons. Starting with the largest tank possible reduces stress from multiple moves and provides better long-term value. Never purchase a juvenile without a concrete plan for adult housing.
Can silver arowanas recognize their owners?
Yes, silver arowanas demonstrate clear recognition of their regular caretakers. They often show excitement when their owner approaches, swimming to the front of the tank and following movements. This recognition extends to associating specific people with feeding times. Some arowanas show wariness or hiding behavior when strangers approach, further demonstrating their ability to distinguish between individuals.
How can I prevent drop eye in my arowana?
Preventing drop eye requires encouraging natural upward-looking behavior. Feed primarily floating foods, vary feeding locations around the tank surface, and consider feeding with tongs from above. Some aquarists place ping pong balls or other floating objects to encourage upward viewing. Avoid sinking foods and bottom-feeding tank mates that might encourage downward focus. Once established, drop eye is generally permanent, making prevention crucial.
What temperature is best for silver arowanas?
The optimal temperature range for silver arowanas is 78°F to 80°F (25.5°C to 26.5°C), though they tolerate 75°F to 82°F (24°C to 28°C). Consistency is more important than exact temperature within this range. Sudden temperature changes stress the fish and can trigger disease. Use reliable heaters appropriate for your tank size, and consider using multiple heaters for redundancy and even heat distribution.
Are silver arowanas legal to keep everywhere?
Silver arowanas are legal to keep in most areas, unlike their restricted Asian arowana cousins. However, some jurisdictions have restrictions on keeping potentially invasive species or large predatory fish. Several U.S. states, Australian territories, and some European countries have specific regulations. Always check local and state regulations before acquiring any exotic fish species, as laws can change and vary significantly by location.
How long do silver arowanas live in captivity?
With proper care, silver arowanas typically live 10 to 15 years in captivity, with some exceptional specimens reaching 20 years. Longevity depends on various factors including water quality maintenance, diet quality, tank size, stress levels, and genetic factors. Fish kept in appropriate conditions from youth generally achieve longer lifespans than those that experience poor conditions during development. This longevity makes them a significant long-term commitment requiring careful consideration before purchase.
Conclusion
The silver arowana represents one of the most rewarding yet challenging species in the freshwater aquarium hobby. Their prehistoric appearance, impressive size, and intelligent behavior make them captivating centerpiece fish for those prepared to meet their substantial requirements. Success with silver arowanas demands commitment to providing appropriate space, maintaining excellent water quality, and offering varied, nutritious diet throughout their potentially 20-year lifespan.
Understanding the natural history and behavior of silver arowanas enhances both the keeping experience and the likelihood of success. These remarkable fish have survived virtually unchanged for millions of years, and their adaptations to life in the Amazon basin inform every aspect of their care requirements. From their surface-dwelling nature to their jumping ability, each characteristic reflects evolutionary pressures that shaped their development.
For those considering adding a silver arowana to their aquarium, honest assessment of available resources and long-term commitment is essential. The initial investment in appropriate equipment pales compared to the ongoing costs of feeding, maintenance, and potential tank upgrades as the fish grows. However, for dedicated aquarists who can meet these requirements, silver arowanas offer an unparalleled opportunity to keep a living piece of prehistoric history.
The growing availability of captive-bred specimens provides a more sustainable option for the hobby while often resulting in hardier fish better adapted to aquarium life. As our understanding of their needs continues to evolve, success rates with breeding and long-term maintenance improve. Whether you're drawn to their impressive appearance, fascinating behavior, or the challenge they present, silver arowanas remain one of the most iconic species in the aquarium hobby. Like the discus fish care guide demonstrates for another challenging species, success with demanding fish comes from thorough research, proper preparation, and ongoing commitment to their specialized needs.
