Bronze Featherback

The Bronze Featherback is a knifefish with a dorsal fin that looks and acts like a feather!

The Bronze Featherback Notopterus notopterus gets its name from the small dorsal fin on its back. This fin stands upright and sways back and forth just like a feather in the wind.

The adult Featherback will be a plain brown while juveniles have dark bars along the entire length of the body. The recent availability of a farm produced albino version (pictured above) is an exciting development. Common names it is known by include Grey featherback, Asian Knifefish, Featherfin Knifefish, and Asiatic Knifefish.

Although not particularly colorful, the Featherfin Knifefish is very interesting to watch and is well worth keeping as a pet. It has a flat elongated body with an arched back. There is a continuous fin along the underside formed by a joining of the caudal and anal fin. This fin undulates, allowing it to move either forwards or back wards, making it a very graceful swimmer. These fish are often confused with the African Knife FishXenomystus nigri. But the African Knife fish can readily be distinguished because it lacks a dorsal fin and is smaller.

The Asian Knifefish species is a member of the Notopteridae family which contains some of the more outgoing species. Some of the members of the Notopteridae family, such as the Clown Knifefish, can grow to huge proportions. The Bronze Featherback can grow to be relatively large in the wild too, reaching up to 24 inches (60 cm). But tank raised fish over 12 inches are rare so you shouldn’t have to worry about eventually dealing with a 2 foot long fish. However, there can be exceptions so you will want to keep their potential size in mind.

The Bronze Featherback need a minimum sized tank of around 40 gallons when young, especially if keeping other fish with them. They will need a larger aquarium of 150 gallons or more as an adult. This knife fish is a rather belligerent species. It will generally get along with peaceful fish bigger than itself, but is very territorial and quarrelsome with others of its own kind. It should be kept singly unless the tank is very large.

These Grey featherback Knifefish are suggested for an aquarist with some fish keeping experience. They can be hard to get adjusted to a new tank. Being nocturnal they need places to retreat during the day as well as open areas for swimming. Once acclimated, they are very hardy fish.

For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care

Habitat: Distribution / Background

The Bronze Featherback Notopterus notopterus was described by Pallas in 1769. They originate in Asia from southern India, Pakistan, Nepal, Bangladesh, Laos, Cambodia, Myanmar and in most coastal river basins of Thailand, Viet Nam, Malaysia, Indonesia Malaysia, Sumatra and Java. Other common names it is know by are Grey featherback, Asian Knifefish, Featherfin Knifefish, and Asiatic Knifefish.

The species is listed on the IUCN Red List as Least Concern (LC) as it has an extremely wide distribution. Its status is not really definitive because Its taxonomy is in an undetermined state at present. It is suggested to most likely be a species complex.

They normally inhabit slow moving streams and canals. They are also found in rivers and ponds. As with many knifefish, during the rainy season they migrate to the flooded forests to breed. There is also recorded evidence that these Knife fish will live in brackish water for short periods of time. They will most likely not survive in a tank that is brackish. In nature this fish feeds on insects, fish, crustaceans and some young roots of aquatic plants.

The Featherfin Knifefish are highly sought after as food fish in their native lands. It is also believed that eating soup made from this fish has health enriching properties, and will cure many diseases. It’s a common remedy given to people with measles.

• Scientific Name: Notopterus notopterus
• Social Grouping: Solitary
• IUCN Red List: LC – Least Concern

Description

The Bronze Featherback can reach up to 24 inches (60 cm) in the wild, but most tank raise specimens won’t grow much larger than 12 inches (30 cm). The body is flat and elongated with an arched back. It has a continuous fin along the underside formed by a joining of the caudal and anal fin. It is a graceful swimmer as this fin allows it to move both forwards and backwards. It also has a very small dorsal fin.

Adults are a plain brown while juveniles will have dark bars along the entire length of the body. The Bronze Featherback pictured above is an albino colorform. This fish looks much like the African Knife fish but can be distinguished by their larger size and presence of a dorsal fin.

• Size of fish – inches: 23.6 inches (59.99 cm) – These fish can get up to Up to 24 inches (60 cm) in the wild, but most tank raise specimens won’t grow much larger than 12 inches (30 cm).
• Lifespan: 15 years

Fish Keeping Difficulty

This Asian Knifefish is suggested for an aquarist with some fish keeping experience. They can be hard to get adjusted to a new tank. They are very hardy fish once they reach a certain size, but can be sensitive to water conditions and some medications when they are small. Many young knifefish die soon after purchase normally due to shock or unsuitable tank and water conditions. Being nocturnal they need places to retreat during the day as well as open areas for swimming. Once acclimated, they are very hardy fish.

• Aquarium Hardiness: Moderately Difficult
• Aquarist Experience Level: Intermediate

Foods and Feeding

The Bronze Featherback is considered an omnivore because they do eat some vegetation, but primarily they eat protein foods. In the wild they begin to eat when the sun sets and continue throughout the night, feeding on insects, fish, crustaceans and some young roots of aquatic plants. In the aquarium they can be fed small fish, worms or small shrimp. Some can be trained to eat freeze dried foods or high quality flake food.

• Diet Type: Omnivore
• Flake Food: Occasionally
• Tablet / Pellet: Occasionally
• Live foods (fishes, shrimps, worms): Some of Diet
• Vegetable Food: Some of Diet – It eats some young roots of aquatic plants in the wild.
• Meaty Food: All of Diet
• Feeding Frequency: Daily

Aquarium Care

This fish is scaleless and very sensitive to water condition changes. A high quality filter is a must! Weekly water changes of about 30-50% are needed. Water condition tests should also be done weekly to make sure levels are not spiking.

• Water Changes: Weekly – Do a 30 – 50% water change weekly.

Aquarium Setup

The Bronze Featherback will spend most of its time near the bottom of the tank. An aquarium of around 40 gallons will work when they are young, especially if keeping other fish with them. They will need a larger aquarium of 150 gallons or more as an adult. Use a high quality filter with low water flow. A UV sterilizer is a smart thing to incorporate into your tank as these fish are very sensitive to medications. The UV sterilizer will kill many diseases.

It requires an aquarium with many hiding places and sheltered areas as well as unobstructed swimming room. Plants are best especially along the back and sides to leave some open area for swimming. Plants with long twisted roots offer hiding places for your Knife Fish. Areas of dense planting, large chunks of bogwood, rock piles and lengths of plastic piping are all possible alternatives. Soft sand is the best choice for the substrate.

It is a largely nocturnal species and prefers dim lighting. Floating plants can help to break up and subdue any light. Provide them with a dimly lit tank and you should have a happy Featherfin. In the right setting the fish will often be seen during daylight hours. Using Moonlight LED lights will give you the best viewing of this amazing fish at night.

• Minimum Tank Size: 40 gal (151 L) – A 40 gallon tank will work when they are small, especially if keeping other fish with them, but they will need a larger aquarium of 150 gallons as adults.
• Suitable for Nano Tank: No
• Substrate Type: Sand
• Lighting Needs: Low – subdued lighting
• Temperature: 75.0 to 82.0° F (23.9 to 27.8&deg C)
• Range ph: 6.0-6.5
• Hardness Range: 2 – 12 dGH
• Brackish: No – These Knife fish will live in brackish water for short periods of time in the wild, but they will most likely not survive in a tank that is brackish.
• Water Movement: Weak
• Water Region: Bottom – The Featherfin Knifefish will spend most of its time near the bottom of the tank.

Social Behaviors

Although they are usually relatively peaceful, individual specimens can become aggressive. They probably won’t kill anything that’s too large to be able to fit into their mouths, but they may damage the fins on fish that are slow or that have long fins. They are very intolerant of their own kind and require a huge tank if you want to try to house 2 in the same tank.

• Venomous: No
• Temperament: Semi-aggressive
• Compatible with:
  • Same species – conspecifics: Sometimes – This knifefish is very territorial and quarrelsome with others of its own kind. It should be kept singly unless the tank is very large.
  • Peaceful fish (): Monitor – This fish is rather belligerent and it will be aggressive towards smaller fish and eating any small enough to be considered a meal.
  • Semi-Aggressive (): Threat
  • Aggressive (): Threat
  • Large Semi-Aggressive (): Threat
  • Large Aggressive, Predatory (): Threat
  • Monitor – They are usually fine with larger tank mates that are big enough to not be considered food, but may damage the fins of slower fish.
  • Shrimps, Crabs, Snails: Threat – is aggressive – In the wild, this fish hunts at night for worms, crustaceans, insects and snails.
  • Plants: Safe

Sex: Sexual differences

Sexual differences are unknown.

Breeding / Reproduction

Breeding has been done in aquariums, but is more of a rarity. One of the earliest reports of breeding was accomplished by Van Pinxteren in 1974 (Datz 27, 364-369), as shared by authors Dr. Rüdiger Riehl and Hans A. Baensc in their book, Aquarium Atlas Vol. 1. They report that, “The fish spawn in the night, dropping eggs to the bottom and on rocks. They were guarded by the male who fanned fresh water over the eggs with his pectoral fins, chasing off all other fishes. The eggs required two weeks to develop and the newly hatched young were sensitive to handling.”

Featherfin Knifefish are mass-produced fish in commercial fish farms in many of their native countries. They are commercially spawned in Thailand but the method being used is not known. In aquariums the eggs are normally laid on the substrate or decor and guarded by the male till they hatch which is usually 2 weeks. Once free swimming these fry will feed on brine shrimp nauplii and microworms. These fish are intolerant of their own kind, so a huge tank would be need and a large influx of cold water added to the tank to trigger spawning.

• Ease of Breeding: Difficult

Fish Diseases

The Bronze Featherback does not have scales which make it more prone to disease. Knifefish are normally the first fish in a tank to show signs of ick and will twitch and rub around the tank. They respond well to most medication and normally heal quickly. NEVER use copper in a Featherfin Knife Fish tank. Overall these fish are hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won’t have to deal with health problems or disease.

Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance. Because these fish eat live food, disease can be passed to them from their foods. Make sure to quarantine live food before feeding.

When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your fish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish is more likely to acquire disease.

As with most fish the Asian Knifefish are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.

Availability

The wild color version of the Featherfin Knifefish is commonly available. The albino version is quite a bit rarer but since they are now being bred in captivity, they should become more commonly available in the near future.

References

• Animal-World References: Freshwater Fish and Plants
• Dr. Rüdiger Riehl and Hans A. Baensch, Aquarium Atlas Vol. 1, Publisher Hans A. Baensch, 1991
• Joseph S. Nelson, Fishes of the World, Wiley, 2006.
• Notopterus notopterus Asian Knifefish, Seriously Fish, 2012
• Notopterus notopterus (Pallas, 1769) Bronze featherback, Fishbase.org
• Notopterus notopterus, The IUCN Red List of Threatened Species