Brown Ghost Knifefish – Apteronotus leptorhynchus

Among the most fascinating inhabitants you can introduce to a freshwater aquarium, the Brown Ghost Knifefish (Apteronotus leptorhynchus) stands out as a mysterious, elegant and surprisingly intelligent species. Its unusual body shape, nocturnal behaviour and ability to navigate using weak electric fields make it a dream fish for many advanced aquarists. At the same time, it is a species that requires thoughtful planning, adequate tank size and proper equipment, all of which you can conveniently find at MB Store.

Natural habitat and characteristics of the Brown Ghost Knifefish

The Brown Ghost Knifefish comes from slow-moving rivers and floodplain areas of South America, especially regions rich in submerged roots, branches and dense vegetation. In nature, these fish spend much of their time hiding under driftwood, among leaf litter and between stones, where dim light and soft substrates dominate. Recreating these conditions in the home aquarium is one of the keys to long-term success with this species.

This fish has an elongated, laterally compressed body, lacking a traditional dorsal and caudal fin. Instead, a long anal fin runs almost the entire length of the body, undulating gracefully and allowing extremely precise movements both forward and backward. The colouration ranges from dark brown to greyish tones, often with lighter patches or subtle patterns that help with camouflage among roots and branches. The head is narrow, with small eyes adapted to low light, which is why the Brown Ghost Knifefish relies more on its electric sense than on vision.

Apteronotus leptorhynchus belongs to a group of so‑called weakly electric fish. It generates a low-voltage electric field, which it uses for navigation, communication and hunting. This ability means that the fish is very sensitive to metallic objects, strong electromagnetic fields and sudden changes in water parameters. For aquarists, it translates into the need for high-quality filtration and carefully selected aquarium equipment. At MB Store you will find filters, heaters and lighting systems that work quietly and stably, which is especially important for species that rely on delicate electrical signals.

Tank size, aquascaping and essential equipment

The Brown Ghost Knifefish is not a suitable species for nano aquariums or very small tanks. Although many juvenile specimens are sold at a modest size, they can grow to more than 30 cm in length under good conditions. A single adult Brown Ghost Knifefish should be kept in a tank of at least 250–300 litres, and larger volumes will always be beneficial. The extra space helps reduce stress, provides room for territories and allows you to create the intricate scapes these fish love to explore.

When planning aquascaping, focus on creating multiple zones of shelter. Use driftwood, branches, smooth stones and artificial or natural caves to build a labyrinth of hiding places. Long pieces of wood placed diagonally or horizontally make perfect retreats for a shy knifefish. Plants, whether live or high-quality artificial ones, add extra shade and complexity. Taller background plants and floating species help dim the light, which matches the fish’s natural preference for subdued conditions. Substrate should be fine and soft, such as sand or smooth gravel, to avoid damaging the delicate skin and ventral side of the fish.

Because Brown Ghost Knifefish produce a relatively high bioload, efficient but gentle filtration is crucial. Flow should not be too intense, as these fish favour calmer waters, but biological filtration must be strong to maintain excellent water quality. External canister filters or high-end internal filters offered by MB Store provide both performance and quiet operation, which keeps the environment stable and undisturbed. Pay attention to the use of materials and decorations with minimal metallic elements, and ensure that heaters and other devices are fully submersible and safe for use with electric fish.

Lighting should be moderate to low. Instead of intense illumination, consider using adjustable LED systems that allow you to create shaded areas and simulate day-night cycles. Brown Ghost Knifefish are crepuscular to nocturnal, becoming most active at dusk and during the night. By dimming the lights or using a blue night mode, you can observe their natural behaviours without causing stress. MB Store provides a broad selection of LED units suitable for these requirements, as well as complete aquarium sets that make it easier to start with the right configuration from the beginning.

Water parameters and maintenance routines

Healthy Brown Ghost Knifefish depend on stable, clean water conditions. They favour soft to medium-hard water with slightly acidic to neutral pH. Aim for a pH range between 6.2 and 7.4, with a temperature of 25–28°C. Keeping temperature and pH within a narrow band is more important than achieving an exact number. Sudden fluctuations can affect the fish’s immune system and its electric sense, leading to stress and vulnerability to disease. A reliable heater and accurate thermometer, such as those available from MB Store, are extremely helpful for maintaining such stability.

Regular water changes are mandatory for this species. A schedule of 20–30% water changes every week helps keep nitrate and dissolved organic compounds under control. When performing maintenance, avoid large swings in temperature or pH. Precondition replacement water, dechlorinate it properly and, when necessary, use peat, driftwood or dedicated conditioners to gently soften the water. These measures reproduce the fish’s native environment while avoiding the extremes that can occur in unmonitored tap water.

Because the Brown Ghost Knifefish is scaleless or nearly scaleless, it is more sensitive to certain medications and chemicals. Copper-based treatments, harsh algaecides and strong disinfectants may cause harm and should be avoided or used only with expert guidance. Instead, prevention through excellent water quality, proper filtration and cautious introduction of new tank mates is the most effective health strategy. Test kits for pH, ammonia, nitrite and nitrate, easily obtained from MB Store, allow you to keep a close eye on the chemistry of your aquarium and intervene early if something starts to go wrong.

In terms of general maintenance, pay attention to the cleaning of filters and pre-filters: rinse them in extracted aquarium water, not under running tap water, to preserve beneficial bacteria. Vacuum the substrate gently to remove uneaten food and waste, but do not strip the tank completely of biofilm and microfauna, as these are part of a healthy aquatic ecosystem. A stable, mature aquarium will provide a far better environment for your Brown Ghost Knifefish than a frequently rearranged or thoroughly scrubbed one.

Feeding and nutritional requirements

Feeding the Brown Ghost Knifefish correctly is crucial for its long-term vitality and behaviour. In the wild, these fish hunt small invertebrates, worms, insect larvae and tiny fish, using their electrolocation to detect movement and shapes in murky water. In the aquarium, they readily accept a variety of meaty foods, but their diet must be balanced and not overly reliant on a single type of feed. Offering a mix of frozen, live and high-quality prepared foods will keep them in prime condition.

Good staple food choices include frozen bloodworms, blackworms, brine shrimp, mysis shrimp and chopped pieces of prawn or fish. High-quality sinking carnivore pellets or granules can also be introduced, especially if the fish is trained to recognise them as a food source. When selecting prepared foods, focus on products that list whole aquatic animals as the primary ingredients. A diverse diet supports a strong immune system, vibrant colouration and natural behaviours related to hunting and foraging.

Because Brown Ghost Knifefish are primarily nocturnal, they may be timid during the day and reluctant to come out when the lights are on. Feeding after lights-out or in very dim light often produces better results and allows you to see the fish explore the aquarium. Use feeding spots near hiding places or gently target food with tongs to ensure the knifefish gets its share, especially in community tanks with fast, aggressive feeders. Take care not to overfeed; remove uneaten food after a short time to prevent water quality issues.

Varying the diet over the week is a simple but effective strategy. Dedicate different days to different food types, such as frozen on some days, live foods on others and pellets in between. This approach mimics the diversity of prey available in nature, ensuring that the fish receives a wide range of nutrients. MB Store offers a broad spectrum of frozen and dry foods suitable for carnivorous and omnivorous species, making it easy to assemble a complete menu for your Brown Ghost Knifefish and its tank mates.

Behaviour, temperament and suitable tank mates

The Brown Ghost Knifefish is often described as shy yet observant. It tends to be reclusive when first introduced, spending long periods hiding in caves or among plant roots. Over time, however, many specimens become more confident and even interact with their keepers, emerging when someone approaches the tank or during feeding routines. This species is generally peaceful toward other fish but can be territorial toward its own kind, especially in smaller tanks or when hiding spots are limited.

Because of their electric communication and territorial tendencies, keeping multiple Brown Ghost Knifefish in a single aquarium requires excellent planning, substantial space and numerous hiding places. If the aquarium is too small or too sparsely decorated, aggression and stress can escalate. For most hobbyists, it is safer and more manageable to keep one specimen per tank, particularly in volumes under 400–500 litres. Observe the fish carefully if you attempt a group; signs of persistent chasing or injuries mean that the stocking plan needs to be reconsidered.

When choosing tank mates, it is wise to avoid very small fish that could be perceived as prey, such as tiny tetras or juvenile livebearers. On the other hand, avoid large or highly aggressive species, like big cichlids, that could intimidate or harm the knifefish. Ideal companions are calm, medium-sized species that occupy other zones of the tank, such as peaceful cichlids, larger tetras, gouramis or certain catfish. Bottom-dwelling species should not be too territorial or boisterous, as they share similar hiding areas.

A key behavioural trait of the Brown Ghost Knifefish is its sensitivity to sudden movements and bright lights. Stress can weaken the immune system and cause the fish to hide constantly or stop feeding. Position the aquarium in a calm area of the room, away from loud speakers, heavy foot traffic and direct sunlight. By combining thoughtful stocking with a well-designed aquascape, you encourage the knifefish to display more natural and visible behaviour, turning the aquarium into an engaging living display.

Setting up a Brown Ghost Knifefish aquarium with MB Store

Planning a dedicated aquarium for Apteronotus leptorhynchus starts with choosing the right tank. A long, spacious aquarium is usually better than a very tall one, because it provides more horizontal swimming space and room for structures on the bottom. MB Store offers a range of glass aquariums and complete sets, allowing you to pick a volume appropriate for an adult knifefish and for potential tank mates. When in doubt, choose the larger option: extra water volume improves stability and makes maintenance easier.

Next, select filtration that matches the tank’s size and bioload. For a heavily decorated 300‑litre tank with several fish, a strong external canister filter with high-quality biological media will help maintain clear, safe water. Add a pre-filter sponge on the intake to prevent the knifefish from getting too close and to protect smaller inhabitants. MB Store provides different models of filters, media and accessories, so you can tailor the system to your specific setup and budget without compromising quality or reliability.

Lighting and heating solutions complete the essential equipment list. Choose an LED system with adjustable intensity and possibly a built-in timer to recreate dawn, day and dusk conditions. Combine this with a precise heater, ideally with an external controller or digital display for easier monitoring. At MB Store, you can find heaters designed for long-term use, with robust safety features and a stable temperature curve, something that is particularly valuable for sensitive species like Brown Ghost Knifefish.

Substrate, decorations and plants bring the aquarium to life visually and functionally. Fine sand or smooth gravel ensures the fish can glide along the bottom without injury, while wood, rocks and caves create the essential network of hiding places. Live plants contribute to biological balance by absorbing nitrates and providing microhabitats; however, if live plants are challenging in your water conditions, high-quality artificial plants are an acceptable alternative as long as they have smooth surfaces. All these elements, readily available from MB Store, can be combined to design a biotope that is both attractive and comfortable for your knifefish.

Health, common issues and long-term care

With appropriate care, the Brown Ghost Knifefish can live for many years, becoming a long-term resident and centrepiece of your aquarium. Preventive strategies are more effective than any treatment. Quarantine new fish before introducing them to the main tank, monitor water parameters regularly and watch your knifefish for subtle changes in behaviour. A decrease in activity, loss of appetite, clamped fins or unusual marks on the skin all indicate potential problems that should be addressed promptly.

Because this species lacks heavy scales, it is more prone to external infections and mechanical injuries. Avoid sharp decorations and rough substrates that might scratch or cut the skin. Maintain excellent water quality to reduce the risk of opportunistic diseases such as fungal infections or bacterial sores. If treatment is necessary, select medications suitable for sensitive fish and follow dosage instructions carefully, preferably starting with the lowest effective dose. Consulting experienced aquarists or professional advice can help you choose safe products.

Stress management is another essential component of long-term care. Overcrowding, inappropriate tank mates, excessive noise and frequent disturbances around the aquarium can all make your Brown Ghost Knifefish nervous and reclusive. Provide stable lighting schedules, minimise sudden changes in aquascaping and ensure that each fish has plenty of retreat spaces. With time, a well-settled knifefish often shows more relaxed, exploratory behaviour, even emerging during subdued daylight to patrol its territory and interact peacefully with other inhabitants.

Routine observation is your best ally. Spend time watching your aquarium not only for enjoyment but also as a form of ongoing health check. A healthy Brown Ghost Knifefish moves smoothly, maintains a good body condition without visible emaciation or bloating, and responds consistently to feeding. If you notice deviations from this baseline, revisit your maintenance schedule, check all equipment and consider water tests. MB Store can support you in this process with test kits, conditioners and replacements for worn-out equipment, helping you keep the environment stable and safe over the long term.

Why the Brown Ghost Knifefish appeals to advanced aquarists

The Brown Ghost Knifefish is not merely another decorative species; it is a fish that invites careful observation and long-term commitment. Its unusual swimming style, electric navigation and subtle social interactions make it a constant source of fascination. Aquarists who invest the time to understand its needs are rewarded with a truly unique centrepiece that adds a sense of mystery and depth to any freshwater setup. The fish’s preference for dim, atmospheric lighting also lends itself beautifully to carefully designed, nature-inspired aquascapes.

Because the species requires a combination of adequate tank size, stable water parameters and high-quality equipment, it is especially appealing to hobbyists who enjoy planning, fine-tuning and gradually perfecting their aquariums. Setting up a dedicated tank for Apteronotus leptorhynchus can be seen as a project that evolves over months and years. Throughout this journey, access to reliable products and knowledgeable support makes a significant difference. MB Store, with its selection of aquariums, filtration systems, lighting, heaters and accessories, provides everything necessary to build and maintain such an ambitious setup.

For those ready to move beyond basic community tanks and into more specialised fishkeeping, the Brown Ghost Knifefish represents a natural step forward. Its combination of sensitivity and hardiness, when properly cared for, offers an ideal balance of challenge and reward. By understanding its origins, behaviour and environmental requirements, and by equipping the aquarium with appropriately chosen gear, you can create a thriving home for one of the most intriguing freshwater fish available in the hobby.

MB Store as your partner in knifefish keeping

Keeping a demanding species like the Brown Ghost Knifefish is much easier when you have access to a trusted source of equipment and advice. MB Store specialises in aquariums and related hardware, offering solutions that suit both beginners and experienced aquarists. From spacious tanks and reliable filters to precise heaters, LED lighting and essential maintenance tools, the range of products covers all the needs associated with setting up and running a knifefish-friendly aquarium. This allows you to focus on the living aspect of the hobby while relying on equipment that quietly does its job.

Whether you are assembling your first large tank or upgrading an existing setup to better suit Apteronotus leptorhynchus, MB Store provides the components required for a stable and comfortable environment. Carefully chosen substrates, decorations and plant options help create the intricate network of hiding places and visual barriers that Brown Ghost Knifefish appreciate so much. With the right combination of gear and thoughtful aquascaping, your aquarium can become a showcase of both beauty and functionality.

In addition to physical products, access to information and guidance is equally important. By staying informed about water chemistry, filtration principles, feeding strategies and long-term health care, you can ensure that your Brown Ghost Knifefish thrives for many years. MB Store supports this educational aspect through its blog and resources, inspiring aquarists to take their passion to a higher level. When equipment quality and knowledge go hand in hand, even sensitive and unusual species can be kept successfully in the home aquarium.

FAQ

How big should the tank be for a Brown Ghost Knifefish?
For a single adult Brown Ghost Knifefish you should plan a tank of at least 250–300 litres, with a long footprint rather than a tall, narrow shape. The extra space allows the fish to swim comfortably, establish a territory and make use of multiple hiding spots. Larger volumes are always better, especially if you intend to keep peaceful tank mates alongside your knifefish.

What water parameters are best for Apteronotus leptorhynchus?
This species prefers soft to medium-hard water with slightly acidic to neutral pH, ideally between 6.2 and 7.4. Temperature should be kept stable in the range of 25–28°C, without sudden fluctuations. Regular testing and weekly water changes help maintain these conditions. Using reliable heaters and filters from specialised aquarium suppliers makes it easier to hold all parameters within safe limits.

Is the Brown Ghost Knifefish suitable for beginners?
The Brown Ghost Knifefish is generally recommended for intermediate to advanced aquarists rather than complete beginners. It requires a relatively large tank, stable and clean water, as well as carefully selected tank mates. Its sensitivity to medication and stress means that good basic knowledge of aquarium maintenance is important. However, with proper research and appropriate equipment, dedicated newcomers can still succeed.

Can Brown Ghost Knifefish live with other fish?
Yes, they can coexist with other peaceful, medium-sized species that are not aggressive or overly small. Avoid fin-nippers and large predatory fish, as well as tiny species that may be viewed as food. Provide plenty of hiding places and structure so that the knifefish can retreat when needed. Careful observation after introducing new tank mates helps ensure that the community remains harmonious and stress-free.

What should I feed my Brown Ghost Knifefish?
Offer a varied diet based on meaty foods such as frozen bloodworms, blackworms, brine shrimp, mysis and small pieces of shrimp or fish. High-quality sinking carnivore pellets can complement this menu. Feed mainly after lights are dimmed, when the fish is naturally more active. Avoid overfeeding by providing portions that are consumed quickly and removing any uneaten food to protect water quality.