Ocellated Spiny Eel

African Spiny Eel

Family: Mastacembelidae Mastacembelus vanderwaaliPhoto © Animal-World: Courtesy Ken Childs

The Ocellated Spiny Eel is a smaller spiny eel with a most definite and unusual color pattern!

The Ocellated Spiny Eel Mastacembelus vanderwaali is an excellent example of a Spiny Eel from the Mastacembelidae Family. As with most members of the spiny eel family, the attractiveness of this eel lies in its unusual color pattern and interesting behavior. This fish has a dark tan to light brown background color. Its featured markings are blotches and short vertical stripes that form a broken line along the entire length of its body. Another common name it is known by is the African Spiny Eel.

Although not considered to be true eels, the body shapes of all members of the spiny eel family are definitely eel-like. This African Spiny Eel has an elongated with a long snout. It is a fairly small spiny eel, reaching about 12 inches (30 cm) in the wild. In the aquarium they rarely get this big however, usually attaining a length of about 6 inches (15 cm),

This Eel is a very attractive little fish. It is also quite durable once established, but is a rather shy fish when first acquired. It gets along well in a community tank but does need hiding places for retreat. It is peaceful with its tank mates as long as they are about the same size. Spiny eels are best kept singly however, as they will also generally fight with others of their own kind. Over time, as spiny eels become comfortable they become more secure. Some will even eventually take food from their keepers hand.

There are many species in the spiny eel family that come from Africa, so fish sold as African Spiny Eels or Ocellated Spiny Eel may not always be Mastacembelus vanderwaali. As long as the spiny eel you purchase is a river dweller, the care and handling should be the same as for this species.

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

Habitat: Distribution / Background

The Ocellated Spiny Eel Mastacembelus vanderwaali was described by Skelton in 1976. (Junior synonym: Aethiomastacembelus vanderwaali) They are found on the Zambezi and Okavango Rivers in Africa. This species is listed on the IUCN Red List as least concern (LC) because it is common in its range with no significant threats identified at present. This species is also called the African Spiny Eel.

They inhabit the moving waters of rivers and streams with sandy to pebbly bottoms, normally with dense with vegetation. They also migrate during the dry season into canals, lakes and floodplain areas. They are nocturnal and will partially bury themselves in the substrate during the day, coming out at night to feed on insect larvae, worms, and other aquatic organisms.

• Scientific Name: Mastacembelus vanderwaali
• Social Grouping: Solitary
• IUCN Red List: LC - Least Concern - The species is common in Upper Zambezi rapids, with no immediate threats to this habitat.

Description

The body of the Half-banded Spiny Eel is elongated with a pointed snout. Both the dorsal and anal fins are extended back to the caudal fin, which is very small. These fish will grow up to almost 6 inches (15.1 cm) in length. Spiny eels have a life span of 8 - 18 years.

The background coloration is a dark tan to light brown. Along the length of its body in the center is a broken line of dark blotches or short vertical stripes. This pattern extends from the tip of its mouth to the rear of the fish. There is additional spotting below this central marking along with a faint spotted line above.

• Size of fish - inches: 5.9 inches (15.09 cm) - This fish usually reaches a more modest 7 inches in the home aquarium.
• Lifespan: 18 years - Spiny eels have a lifespan of 8-18 years.

Fish Keeping Difficulty

Eels are generally suggested for an aquarist with some experience rather than the beginner fish keeper. This eel can be a bit sensitive to change and usually takes awhile to get over its shyness. The first few weeks can be extremely difficult getting them to eat. They do require extremely pristine water. They have very small scales protecting their body so are prone to fungus and parasites and very sensitive to medications. These fish respond poorly to copper based medications, so these should be avoided. If cared for properly, these eels can live for a long time.

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

Foods and Feeding

The Ocellated Spiny Eels are carnivores. In nature they feed at night on insect larvae, worms, and other benthic organisms. Like all spiny eels they prefer a diet of live and fresh frozen foods such as brine shrimp, black worms, earthworms or bloodworms. Some can be trained to eat freeze dried brine shrimp or bloodworms but this is not something that can be counted on. They will also eat small fishes so make sure their tank mates are too large to be able to fit into their mouths.

These Eels are very shy when first introduced to a new environment and often die of starvation. It is best to feed these fish at night and make sure food makes it to the bottom. Do not house with other aggressive feeding bottom dwelling fish until the eel has become comfortable with its environment.

• Diet Type: Carnivore
• Flake Food: No
• Tablet / Pellet: Occasionally - Not all specimens will accept processed foods.
• Live foods (fishes, shrimps, worms): Some of Diet
• Meaty Food: All of Diet
• Feeding Frequency: Weekly - Eels only need to be fed a couple of times a week, and sometimes will eat even less.

Aquarium Care

The most important thing for these eels is that they always have clean and well-oxygenated water. Frequent water changes of about 30% a week are needed for this eel. With your weekly water change make sure to vacuum the gravel to remove all excess food and waster. but It's best not to remove any bio film on rocks and decor. A magnet algae cleaner normally does a great job in keeping the viewing pane clear.

• Water Changes: Bi-weekly - Water changes of about 30% weekly.

Aquarium Setup

Ocellated Spiny Eels will spend most of their time on the bottom of the aquarium. It is advisable to keep them in a tank that is at least 36 inches long and about 35 gallons. These fish require pristine water. They do best in a soft to medium water with good water movement that provides plenty of oxygenation. The tank water should turnover at least 10-15 times per hour. An undergravel filter is a great choice for these fish as it creates high oxygen through out the tank as well as reducing the waste. A canister filter or powerheads and airstones can be introduced to achieve proper flow and oxygenation.

They like a dimly lit aquarium or one with floating plants to help subdue the light. Provide a tank with a sand or fine gravel substrate as they may burrow into it. Make sure they have plenty of hiding places among roots, rocks, or other decor so they will feel secure in their new home. Floating plant cover is great but plants buried in the substrate may get uprooted. Provide a tight fitting lid as spiny eels are escape artists.

• Minimum Tank Size: 35 gal (132 L)
• Substrate Type: Sand/Gravel Mix
• Lighting Needs: Low - subdued lighting - In moderately lit tanks a lot of shaded hiding places are needed. Providing floating plants will also help subdue the light.
• Temperature: 74.0 to 82.0° F (23.3 to 27.8° C)
• Range ph: 7.4-8.4
• Hardness Range: 5 - 15 dGH
• Brackish: No
• Water Movement: Moderate
• Water Region: Bottom - Spiny eels will spend most of their time on the bottom of the aquarium.

Social Behaviors

They are a nocturnal species but are generally peaceful and shy. Small fish are part of their natural diet in the wild so fish under about 2 inches are at risk, however they mostly ignore other tankmates. Some species of spiny eels can get territorial and aggressive with their own kind so a general rule of thumb is to keep them singly unless you plan to breed.

These eels are very shy when first introduced to a new tank and are known to be too shy to eat at times. It is wise not to have tank mates like catfish or loaches, at least not until your spiny eel is settled in. These fish will simply take any food offered too quickly and the eel will not get comfortable enough to feed freely.

• Venomous: No
• Temperament: Peaceful - This fish is not aggressive but will eat tank-mates that are small and slow enough.
• Compatible with:
  • Same species - conspecifics: Sometimes - Generally spiny eels should be kept singly unless the aquarist is hoping to breed them or has a large tank with enough room for each eel to have undisturbed territories. Then try to keep like sized fish together.
  • Peaceful fish (): Safe - As long as tank mates won't fit in the eels mouth they are normally safe.
  • Semi-Aggressive (): Monitor
  • Aggressive (): Threat
  • Large Semi-Aggressive (): Threat
  • Large Aggressive, Predatory (): Threat
  • Slow Swimmers & Eaters (): Monitor
  • Shrimps, Crabs, Snails: May be aggressive
  • Plants: Safe - Make sure roots are secure as eels like to uproot plants.

Sex: Sexual differences

Sexual differences are unknown and it is almost impossible to identify the sexes, though a mature female may be more full bodied.

Breeding / Reproduction

The Ocellated Spiny Eel has not been bred in captivity. Only a few spiny eels have been bred in the aquarium, possibly because they are generally kept singly rather than in a group where a male and female can find each other. Though it is not documented what makes them spawn, trying to emulate the bounty of the flood season can help stimulate breeding behavior. Feed more and higher quality food than you normally would and providing an influx of clean water. Their courtship lasts for several hours, where they chase each other and swim in circles.

The eggs are deposited among floating plants. They are sticky so will adhere to the plants and then hatch in 3 to 4 days. The fry becoming free swimming a few more days after that and should be fed nauplii. The fry are something of a challenge to raise as they are susceptible to fungal infections. Regular water changes and the use of an antifungal water treatment can help.

• Ease of Breeding: Unknown

Fish Diseases

Eels are prone to diseases caused by parasites and fungus, so take caution when introducing these fish to an established tank. Eels are also very sensitive to medications used to treat many diseases; a separate hospital tank is needed. Very low water temperatures and condition changes can also cause stress to this fish which makes them even more prone to disease. Take great care when netting eels as they have very delicate and scraps can make them even more prone to disease.

The most common disease that an eel is susceptible to is Ich. Ich is short for Ichthyophthirius, also known as "white spot disease". It is a parasite that can attack nearly all aquarium fishes, but you'll find that Eels are often the first to be attacked. Take great care in treating ick as eels are very sensitive to the medications used to treat it. Often the dose is half of what is normally used. If nervous or unsure about medications, use Reef safe medications.

An outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping these sensitive types of fish, it is common to catch deteriorating water conditions and disease before other fish are affected. The best way to proactively prevent disease is to give your Ocellated Spiny Eell 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 will is more likely to acquire 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. 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

Although not considered rare, collecting expeditions to their home waters are rare. Consequently the Ocellated Spiny Eel or African Spiny Eel are not commonly available.

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.
• Mastacembelus vanderwaali (Skelton, 1976) Ocellated spiny eel, Fishbase.org
• Mastacembelus vanderwaali, The IUCN Red List of Threatened Species

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