The Variable Lampeye Killifish is an extremely beautiful little fish, but keeping it takes a great deal of dedication!

The Variable Lampeye Procatopus similis is a pretty small fish, reaching only about 2 1/2 inches (6 cm) in length. It is is also known as the Nigerian Lampeye and Yellow Lampeye. Although the males are more colorful than the females, the Variable Lampeye species are incredibly beautiful. And true to ther name, they are truly quite variable in color.

This is an amazingly beautiful species that is worth keeping if you are an advanced aquarist. Over much of their body they have an intense green-blue coloration with a strong red stripe running along their back. The tail fin and fins are adorned in yellows, and sometimes blue or red, with an occasional edging in red. Their bright red eyes and incredible body coloration are lures that will draw you in. Although they are hard to resist, these fish are a challenging to keep.

To successfully keep the Variable Lampeye takes a good deal of devotion. They will need a good sized aquarium, at least 30 gallons, and close attention to providing good water quality and good food. A planted tank is an excellent way to showcase these specimens.

These fish are especially pleasing when contrasted against a dark substrate in a well lit aquarium. No one should attempt to keep this species however, unless they are prepared to invest a substantial amount of time and resources into their care. If you feel you’re up to the challenge, keeping the Variable Lampeye Killifish in good condition is immensely satisfying.

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

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Cyprinodontiformes
  • Family: Poeciliidae
  • Genus: Procatopus
  • Species: similis
Variable Lampeye – Quick Aquarium Care
  • Aquarist Experience Level: Advanced
  • Size of fish – inches: 2.4 inches (5.99 cm)
  • Minimum Tank Size: 30 gal (114 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Difficult
  • Temperature: 75.0 to 79.0° F (23.9 to 26.1&deg C)
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Habitat: Distribution / Background

The Variable Lampeye Procatopus similis was described by Ahl in 1927 and are found in Africa. They are found in Nigeria and also they are found in central Africa In Lower Guinea, and in west and east Cameroon, southward to the Lokundje River. In western Africa they are found in on the coastal plains in rain and secondary forests in Southern Nigeria, and they are found on Bioko island (former Fernando Poo), Equatorial Guinea. Other common names they are known by are the Variable Lampeye Killifish, Nigerian Lampeye, and Yellow Lampeye.

The Variable Lampeye Killifish primarily inhabit the fast moving waters of small rivers and streams, mostly in coastal rivers and brooks. This fish is known as a benthopelagic species. This means they live and feed near the bottom (benthic) as well as in midwaters or near the surface (pelagic). They do not migrate as many of the fish in this region do. They feed on insect larvae, small aquatic insects, small crustaceans, and river worms.

  • Scientific Name: Procatopus similis
  • Social Grouping: Groups
  • IUCN Red List: LC – Least Concern – This fish has a wide distribution with no known major widespread threats.


The Variable Lampeye is a small fish, not quite reaching up to 2 1/2 inches (6 cm) in length with a life span of 4 years. Its is elongated with a slightly arched back giving it a rather irregular diamond shape. The dorsal fin is set towards the back half of the body and the scales are round. The head is flattened on top, the mouth is upturned, and they have no barbels. Like the other members of the Procatopus genus, they have a thorn-like apendage on the lower portion of the gill cover.

These fish are very beautiful and true to their name, are quite variable in color. They have a light to intense green-blue coloration over much of the body that becomes a pale white towards the front on the abdomen. There is a bold red stripe along the back starting at the mouth and extending through the caudal peduncle. The tail is yellowish or blue with red margins on the top and occasionally on the bottom. The fins on the male are a yellowish color, less commonly they can be blue or red color, and sometimes they are outlined in red. There can be red spots, usually in a double row on the anal and tail fins that sometimes merge into a band. The fins on the female are transparent. Males are more colorful than females.

  • Size of fish – inches: 2.4 inches (5.99 cm)
  • Lifespan: 4 years

Fish Keeping Difficulty

The Variable Lampeye Killifish is one of the more difficult Killifish to keep and not recommended for the beginner. They are a schooling fish and can be relatively expensive so the first obstacle is being able to afford 6 or more. They do best with salt added to the tank. Then these fish are so sensitive to water changes to it is hard to be able to keep up with their maintenance. An advanced and very knowledgeable fish keeper prepared to devote extra time to their care is best suited for these fish.

  • Aquarium Hardiness: Difficult – They are are extremely sensitive to water quality changes, so are hard to maintain.
  • Aquarist Experience Level: Advanced

Foods and Feeding

Variable Lampeye Killifish are carnivores. To keep them in good condition, they should be fed a variety of fresh or frozen foods such as brine shrimp, bloodworms or mosquito larvae.

  • Diet Type: Carnivore
  • Flake Food: Yes
  • Tablet / Pellet: Occasionally
  • Live foods (fishes, shrimps, worms): Half of Diet
  • Meaty Food: All of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

Variable Lampeyes can be difficult to keep. Their water must be kept exceptionally clean. Good filtration is a must along with regular water changes. Invest in a lot of test strips and test your water often to ensure there are no condition changes. Water changes of 30% weekly or more are needed for this sensitive fish. Smaller, but more frequent water changes of 10 to 20% can help even more to maintain high water quality.

  • Water Changes: Weekly – Weekly water changes or more are needed for this sensitive fish.

Aquarium Setup

The Variable Lampeye is a species that will swim near the middle of the tank. Although these fish are not large, they need pristine water. A tank of at least 30 gallons is recommended. They come from flowing water so they need a good amount of current to keep them happy and the water should also be high in oxygen. A very high quality filter is needed to aid in keeping the water conditions stable and an undergravel filter would be a good addition as well. These filters do a great job of keeping the entire tank oxygenated. A good powerhead is needed to make sure that there is a constant current.

As with many fish, the lampeyes will do best and are most effectively displayed in tanks which simulate their natural habitat. A dark substrate in a dimly lit aquarium will showcase this fish. Any easy to care for substrate will work best because this fish requires constant tank cleaning. These fish prefer well planted tanks with open areas for swimming. However, like most killifish, it is an excellent jumper so make sure to have a secure cover.

  • Minimum Tank Size: 30 gal (114 L)
  • Suitable for Nano Tank: Sometimes
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 75.0 to 79.0° F (23.9 to 26.1&deg C)
  • Range ph: 6.0-8.0
  • Hardness Range: 5 – 12 dGH
  • Brackish: Sometimes
  • Water Movement: Strong
  • Water Region: Middle – This is a species that will swim near the middle of the tank.

Social Behaviors

Variable Lampeye Killifish are very peaceful and can be kept with other peaceful species that enjoy similar conditions. Some tank mate suggestions include smaller danios, hill stream loaches, many of the South American characins and smaller Loricariids. Like all Killifish, they can also do well when kept in a species tank with a school of their own kind.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species – conspecifics: Yes – Groups of this species needs to consist of 6 or more individuals.
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Threat
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Monitor
    • Shrimps, Crabs, Snails: Safe – not aggressive
    • Plants: Safe

Sex: Sexual differences

Variable Lampeyes can be difficult to sex. Males are larger and more colorful and their anal fin is more pointed, but these differences are all very slight.

Breeding / Reproduction

The Variable Lampeye is a difficult fish to breed and no one seems to have a surefire method to get them to spawn. If you want to attempt breeding, contact your local Killifish Association to try and find someone that has had success in your area.

  • Ease of Breeding: Difficult

Fish Diseases

Variable Lampeye Killifish are not the most hardy and disease can be a problem caused my the slightest water condition changes. Killifish are primarily susceptible to velvet and bacterial infections if good water quality is not maintained. 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.

When keeping more sensitive types of fish like the Variable Lampeye, it is common for these fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Variable Lampeye Killifish 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.

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.


The Variable Lampeye Killifish, also called the Nigerian Lampeye or Yellow Lampeye, are occasionally available.