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Killifish Care Guide: Species, Tank Conditions, Diet, and Breeding

Killifish, (Aphyosemion striatum) is a captivating species found in freshwater habitats worldwide, renowned for their striking colourations and unique behaviours. Native to ecosystems from temporary ponds in Africa to slow-moving streams in South America, these fish exhibit a myriad of adaptations.

Interestingly, while many species share fundamental care needs, their diversity means that some, especially the annual and non-annual types, have distinct requirements reflecting their natural habitats. A rare fact about these fish is their ability in some species to survive in ephemeral water bodies by producing eggs that can endure prolonged droughts, only hatching when conditions are optimal.


Killifish Facts & Overview

Killifish Fact:Details
Scientific Name:Aphyosemion striatum but can vary buy species
Common Names:Killifish, Bluefin Notho, Striped Panchax, and many more
Care Level:Moderate (may vary with species)
Native Region:Freshwaters worldwide, notably Africa and South America
Lifespan:3 months to 5 years, depending on species
Size:Typically 2-3.5 inches (5-9 cm, varies by species)
Diet:Primarily insectivores but also Carnivore
Minimum Tank Size:At least 10 gallons (38 litres) for most species
Compatibility:Generally peaceful; best with fish of similar size

Species Summary

Killifish belong to the Cyprinodontiformes order, encompassing over 1,000 species distributed globally. Typically small in size, most measuring between 2 to 3.5 inches, they’re recognised for their vibrant colours and distinctive patterns. Native to varied habitats, from African deserts to South American rainforests, they’ve adapted uniquely to their environments.

Some species, lay drought-resistant eggs in temporary water bodies, ensuring survival across seasons. While many killifish thrive in similar aquatic conditions, their vast diversity demands tailored care approaches for each type.

Killifish Lifespan

They have varied lifespans depending on their species and environment. Typically, they live between 1 to 5 years. Remarkably, annual killifish species have shorter lives, often just a year, aligning with their unique adaptation to seasonal water bodies.

In contrast, non-annual species tend to have longer lifespans. Proper care and optimal tank conditions can significantly influence their longevity.

Appearance & Size

Killifish display a remarkable range of colours and patterns, making them visually striking additions to aquariums. Their vivid hues can range from iridescent blues to fiery reds, reflective of their diverse origins. Size-wise, they’re typically petite, with most species measuring between 2 to 3.5 inches in length.

blue dot Killifish

Different Types of Killifish

While broadly categorised under one name, exhibit a myriad of species-specific attributes and behaviours. The richness in their variety is primarily seen in the differentiation between annual and non-annual types, each with unique evolutionary adaptations and care requirements.

Annual Killifish

Originating primarily from seasonal water bodies like temporary ponds and streams, annual killifish have a remarkable adaptation: they produce eggs capable of surviving extended drought periods. These eggs lie dormant in the dry mud, only hatching when the rains return.

Due to their ephemeral habitats, their lifespan is typically shorter, often spanning just a year. For fish keepers, understanding their unique life cycle is essential for providing optimal care.

Non-annual Killifish

In contrast to their annual counterparts, non-annual killifish come from stable aquatic environments without extreme seasonal changes. These fish have longer lifespans, often exceeding a year, and their eggs hatch in more predictable patterns.

When housed in aquariums, they often require consistent water conditions that mimic their natural habitats. Recognising the distinctions between annual and non-annual species is vital for any fish keeper aiming to nurture these diverse creatures effectively.

Killifish variety

Behaviour/Compatibility for Killifish

Typically placid, but they can be territorial, especially during breeding periods. They are often found dwelling in the middle to top regions of the tank, showcasing their vibrant colours. While they can coexist with many species, it’s essential to pair them with tank mates that won’t outcompete or bully them.

What Are Good Tank Mates?

  • Tetras: Small, peaceful, and found in similar water conditions.
  • Rasboras: Another petite species that prefers the top layers of water.
  • Corydoras Catfish: Bottom dwellers, they won’t intrude on the killifish’s territory.
  • Shrimps: Like cherry or amano shrimps, they’re non-aggressive and add diversity to the tank.
  • Dwarf Gouramis: Peaceful by nature, they coexist well with killifish.
  • Snails: Great for tank cleaning and won’t disturb the fish.

Unsuitable Tank Mates

  • Large Cichlids: Their territorial and sometimes aggressive nature can pose a threat.
  • Oscars: Known to be predatory towards smaller fish.
  • Arowanas: Predators by nature, they’ll likely see small killifish as food.
  • Bettas: Especially male bettas, can be aggressive and territorial.
  • Barbs: Some, like the Tiger Barb, are known fin-nippers.
  • Plecos: Larger species can be aggressive and may disturb killifish.
  • Aggressive Catfish species: Like the Pictus Catfish, they might chase or nip at killifish.

Aquarium Requirements

Ensuring optimal conditions for killifish within an aquarium is paramount for their health and well-being. With their diverse origins and unique needs, it’s imperative for aquarists to provide an environment that closely mirrors their natural habitat.

Minimum Tank Size

Though small, these fish require adequate space for swimming and exhibiting natural behaviours. A minimum of 10 gallons is recommended for a small group. However, if planning on breeding or housing multiple species, a larger tank may be necessary.

Other Tank Considerations

  • Substrate: Opt for fine-grained sand or soft substrate to mirror their natural habitats and protect their delicate fins.
  • Plants: Live aquatic plants provide shelter, spawning grounds, and make the environment more naturalistic.
  • Filtration: A gentle, adjustable filter ensures clean water without creating strong currents that could stress the fish.
  • Lighting: Moderate lighting that simulates their natural environment is preferred.

Natural Habitat

Killifish are found in a variety of freshwater habitats around the world, from shallow temporary ponds in Africa to slow-flowing streams in South America. These habitats are often densely planted with moderate to low light conditions. Understanding their origin aids in replicating a comfortable environment.

Killifish among plants

Water Requirements

  • Temperature: Ranges between 20°C to 26°C, though specific needs can vary based on species.
  • pH Level: Generally, a pH of 6.0 to 7.5 is suitable.
  • Hardness: Soft to moderately hard water, with a dGH of 5-12, is preferred.

Regular water testing is essential to ensure these parameters are maintained and to keep the environment safe for the fish.

Housing Recommendations

  • Decoration: Include driftwood and rocks to create hiding spots and territories.
  • Safety: Ensure the tank has a tight-fitting lid as killifish are known jumpers.
  • Tank Mates: Always consider the compatibility of other fish and ensure no overcrowding.
  • Maintenance: Regular water changes and tank cleaning prevent the build-up of harmful toxins.

Compatible Plants for Killifish Aquariums

Plants enrich killifish tanks by offering shelter, improving water quality, and recreating natural habitats. Choosing compatible plants aids in achieving a harmonious environment that caters to the well-being of the fish.

Benefits of Aquatic Plants

  • Oxygenate the water
  • Absorb harmful nitrates
  • Provide spawning grounds
  • Offer refuge, mimicking wild habitats

 Recommended Plants

  • Water Lettuce: Floating plant with long roots, offering shade and refuge.
  • Duckweed: Surface-covering plant that moderates light and absorbs nitrates.
  • Dwarf Sagittaria: Carpeting plant, providing a natural substrate cover.
  • Java Moss: Adaptable and provides fine shelter, ideal for fry.
  • Hornwort: Fast-growing, aids in water purification.
  • Anubias: Hardy and low-maintenance, provides structure in mid-ground.
  • Java Fern: Thrives in varied conditions, offers dense foliage.
  • Vallisneria: Grass-like appearance, suitable for background placement.
  • Amazon Sword: Broad leaves, great for background and creating shade.
Killifish top and bottom dwelling

Diet and Nutrition

Providing a balanced diet is paramount to ensuring the health and vibrancy. These fish have specific dietary needs that, when met, contribute to their overall well-being, colour vibrancy, and breeding success. Understanding their natural diet and catering to it in an aquarium setting ensures longevity and overall vitality.

 What Do Killifish Eat?

In the wild, killifish are primarily insectivores, feeding on a variety of small insects, larvae, and crustaceans. They often thrive on a diet rich in live or frozen foods, which emulate their natural feeding habits. Their agile, middle-to-surface dwelling nature makes them adept hunters, eagerly pursuing prey within their environment.

Ideal Food And Diet

Live Foods:

  • Brine shrimp: Easily cultured, a favourite among many killifish species.
  • Daphnia: A nutritious water flea providing essential fatty acids.
  • Worms: Microworms or blackworms can be offered in moderation.

Frozen Foods:

  • Bloodworms: High in protein, but should be fed sparingly.
  • Mysis shrimp: A wholesome option providing both protein and essential fats.

Flake and Pellet Foods:

  • High-quality, specially formulated diets can supplement live or frozen feedings.


  • Some species occasionally graze on soft algae or plant matter.

Feeding Recommendations

  • Offer a varied diet to ensure all nutritional needs are met.
  • Feed in small quantities, ideally 1-2 times daily, to prevent overfeeding.
  • Observe during feeding to adjust amounts and identify preferences.
Killifish face close up

Breeding Killifish

Breeding killifish is a fascinating endeavour, allowing aquarists to observe the intricate lifecycle of these vibrant fish. Their breeding habits and requirements can differ greatly depending on the species. With the right knowledge and environment, successful breeding is attainable, paving the way for the next generation of these captivating creatures.

Breeding Level – Easy to Difficult

Killifish breeding difficulty varies considerably among species. Some are relatively easy to breed, requiring minimal intervention, while others may demand precise water parameters and specific breeding grounds. Being aware of the intricacies of each species is paramount for breeding success.

Annual Killifish

Annual killifish hail from temporary water bodies and have a unique reproductive strategy to match:

  • Lifespan: Their natural lifespan is typically a year or less, aligning with the seasonal existence of their habitats.
  • Egg Diapause: These killifish lay drought-resistant eggs that can endure dry periods. During this ‘diapause’, embryo development halts until favourable conditions return.
  • Breeding in Captivity: To simulate their natural breeding cycle, a drying period followed by re-wetting is essential. Peat moss is often used as a substrate for egg laying, which can later be dried and stored.

Breeding Non-Annual Killifish

Non-annual killifish, found in permanent water bodies, have a more conventional breeding approach:

  • Spawning Sites: They often prefer dense vegetation or spawning mops to lay their eggs.
  • Egg Development: Unlike annuals, their eggs hatch in a shorter span, usually within 2-3 weeks.
  • Breeding in Captivity: Providing ample hiding spots and a protein-rich diet can encourage spawning. Regular water changes and mimicking natural light cycles can further enhance breeding conditions.

Breeding Tips

  • Research the specific breeding needs of the chosen species.
  • Maintain pristine water quality and closely monitor water parameters.
  • Separate breeding pairs or groups to create a dedicated breeding tank.
  • Ensure a nutritious diet to condition fish for breeding.

Successful breeding not only provides a deeper appreciation for killifish but also contributes to the conservation of species, especially those that are rare or endangered in the wild.

Killifish side view

 Additional Considerations

Keeping killifish is a rewarding experience, offering both aesthetic pleasure and the joy of observing their natural behaviours. However, it’s vital to weigh the pros, cons, and responsibilities. Knowing where to source these fish is equally crucial, ensuring healthy specimens and supporting responsible trade.

Should You Keep Killifish?

Killifish are undoubtedly captivating, but they’re not for everyone. Here are points to ponder:


  • Diversity: They come in a plethora of colours and patterns, making them a visual treat.
  • Behaviour: Observing their natural behaviours, especially during courtship and breeding, is fascinating.
  • Community Tanks: Many species are peaceful and can thrive in community setups.


  • Specific Needs: Some species require precise water parameters and diets.
  • Short Lifespans: Particularly with annual species, their lifespans can be brief.
  • Breeding: While rewarding, breeding certain species can be complex.

Considering these factors will help in making an informed decision about whether killifish are the right fit for your aquarium.

Where to Buy Killifish

Finding the right source is pivotal to ensuring you obtain healthy and ethically sourced killifish.

  • Local Fish Stores: Reputed stores often stock a variety of killifish. Engaging with knowledgeable staff can provide insights into the fish’s origin and health.
  • Killifish Associations: Many countries have dedicated associations, offering sales, swaps, and auctions.
  • Online Retailers: Ensure they’re reputable and read reviews. Some specialise solely in killifish and provide detailed species information.
  • Fish Shows & Conventions: These events often feature rare or unique species, giving you access to a broader range of options.

Purchase Tips

  • Research the specific killifish species you’re interested in to identify their needs and compatibility.
  • Quarantine new fish to ensure they’re disease-free before introducing them to your main tank.
  • Support breeders and sellers who prioritise ethical and sustainable practices.


Are Killifish aggressive?

Most are peaceful, but some can be territorial or aggressive, especially during breeding. Always research specific species for temperament and compatibility.

Do Killifish jump out of tanks?

Yes, they are known jumpers. It’s advisable to have a well-fitted lid on their tank to prevent them from leaping out and risking desiccation.

Will Killifish eat small fish?

Some larger species may prey on smaller fish, especially fry. It’s essential to choose tank mates of similar size and research species-specific tendencies to ensure compatibility.

Are Killifish related to Guppies?

No, killifish and guppies are not closely related. While both are freshwater fish, killifish belong to the family Cyprinodontidae, and guppies are part of the Poeciliidae family.

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