Killifish Care Guide: Simple Steps to Keep Your Fish Thriving

Killifish are truly a sight to behold – these small, torpedo-shaped freshwater fish come in a dazzling variety of colors and patterns. They’re more than just a pretty face, though! Their straightforward care requirements make them a popular choice for aquarists of all experience levels.

In this care guide, we will cover everything you need to know to keep your Killifish happy and healthy. From tank setup and water parameters, to their diet and tank mates, we’ve got you covered. So let’s dive in and explore the fascinating world of Killifish!

Species Overview

Killifish are small, colorful fish belonging to the order Cyprinodontiformes, which includes over 1000 different species across 14 families. They are known for their vibrant colors and unique patterns, making them popular among fish enthusiasts. These torpedo-shaped fish can be found in various habitats, ranging from freshwater to brackish ecosystems.

To provide proper care for your killifish, it’s important to familiarize yourself with their specific needs and preferences. Here’s a table showcasing the essential information you should know about killifish:

Property Information
Scientific name Cyprinodontiformes
Common names Killifish, Toothcarps
Distribution Worldwide
Size 1-6 inches (2.5-15 cm)
Lifespan 1-5 years
Diet Carnivorous
Temperament Peaceful
Minimum tank size 10 gallons (37.85 L)
Temperature 72-75°F (22-24°C)
pH 6.0-7.0
Water hardness 4-15 dGH
Care level Beginner to Intermediate
Filtration/Water Flow Low
Water type Freshwater, Brackish
Breeding Egg-laying
Breeding difficulty Moderate
Compatibility Species only, community

By understanding the essential requirements and characteristics of killifish, you’ll be better equipped to create a suitable environment and care routine for these captivating aquatic pets.

Origins and Natural Habitat

Killifish are found in tropical and sub-tropical waters across the world, except in Australia and Antarctica. They inhabit a variety of environments, like temporary pools, swamps, creeks, and shallow streams. Some species even explore brackish estuary habitats.

In their natural habitat, Killifish prefer living in shallow, slow-moving waters. To replicate these conditions in your aquarium, maintain a water pH balance between 6.0 and 7.0 and keep the hardness between 4 and 15 dGH. Ensure that the water flow in the tank is low to provide a more authentic environment for your Killifish.

When it comes to their behavior, Killifish are generally docile and can adapt well to different water conditions. They coexist peacefully with other fish, as long as the tankmates are not too small, which might make them potential prey.

Physical Characteristics

Size and Shape

Killifish are generally small, slender, and pike-shaped, which makes them excellent swimmers. Their size typically ranges from 1 to 2 inches (2.5 to 5 cm) in length. This compact size allows them to thrive in various tank environments.

Color and Markings

The diverse colors and markings of Killifish can truly grab your attention. Males exhibit brighter colors compared to females. Their bodies usually display a mix of yellow and blue hues, with bright orange spots and stripes. Furthermore, their bellies and jaws tend to be white, while their eyes can sometimes appear green. These vibrant colors make Killifish attractive additions to your aquarium.


Killifish have a unique lifespan, which varies depending on their species. Some are annuals, living only for about a year, while others can live up to 5 years. They are widely known for their vibrant colors and patterns, making them a beautiful addition to your aquarium. To maximize your killifish’s lifespan, it’s essential to maintain proper tank conditions, provide a well-balanced diet, and ensure plenty of hiding places with live plants. Following these guidelines will not only increase your killifish’s longevity but also contribute to a thriving and visually stunning aquatic environment.

Killifish Species

Killifish are a diverse group of fish belonging to the order Cyprinodontiformes, encompassing 14 different fish families and over 1000 different species. They are known for their vibrant and diverse colors, as well as their unique breeding behavior. In this section, we’ll explore the two main types of killifish: annuals and non-annuals.


Annual killifish have a unique and fascinating life cycle. They inhabit temporary bodies of water, such as ponds and puddles, which dry up seasonally. As a result, these fish have developed an incredible ability to adapt and survive in these harsh conditions. Their lifespan is generally shorter, ranging from six months to a year.

A notable example of an annual killifish is the Nothobranchius guentheri, also known as the redtail notho. This species is endemic to Zanzibar and has predominantly red fins. Redtail nothos typically grow between 2 to 3 inches in size.

When caring for annual killifish, it’s essential to replicate their natural habitat as closely as possible. This includes providing:

  • Soft, acidic water with a pH between 6.0 and 7.0
  • Water hardness between 4 and 15 dGH
  • A well-planted tank with hiding spots for fish to rest
  • Low water flow to mimic their natural environment


Non-annual killifish, on the other hand, inhabit permanent bodies of water and typically have longer life spans than their annual counterparts. They come in various colors and patterns, making them popular choices for aquarium enthusiasts.

One example of a non-annual killifish is the bluefin notho, a beautiful and colorful species. Like annual killifish, the care requirements for non-annuals largely revolve around replicating their natural habitat. This includes:

  • Maintaining water parameters within the preferred pH and hardness ranges
  • Providing ample plant cover and hiding spots
  • Ensuring a low water flow within the tank

Remember, understanding the specific needs of your chosen killifish species is crucial for their health and well-being. By providing proper care and replicating their natural habitat as closely as possible, you can enjoy the beauty and fascinating behavior of these fish in your own aquarium.

Aquarium Setup

Setting up an aquarium for your Killifish friends is a crucial step in ensuring their well-being and happiness. In this section, we’ll guide you through the process of creating a suitable environment for them, covering important aspects such as tank size, substrate, filtration, and water parameters.

Tank Size

When it comes to selecting a tank size, a general rule of thumb is to opt for a 10-gallon tank. This should provide ample swimming space and a comfortable environment. However, if you plan on keeping a larger community of Killifish or adding tank mates, it’s always a good idea to invest in a bigger aquarium.


Killifish prefer a soft and sandy substrate in their tank, as it closely mimics their natural habitat. This type of substrate will also encourage the growth of beneficial bacteria and promote overall tank health. Be cautious with sharp or coarse substrates, as they can potentially damage the Killifish’s delicate skin.


A low water flow is essential to replicate the natural habitat of Killifish. Opt for a decent sponge filter or a gentle hang-on-back filter to maintain proper water quality without creating a strong current. Remember to regularly clean and maintain your filtration system for optimal performance.

Water Parameters

Killifish thrive in specific water conditions, so it’s essential to maintain the right balance for their well-being:

  • Temperature: Maintain a consistent water temperature between 72-78°F.
  • pH Level: Keep the water pH between 6.0 – 7.0.
  • Water Hardness: Aim for a value between 4 and 15 dGH.

It’s important to continuously monitor and adjust the water parameters as needed to ensure your Killifish thrive in a healthy environment. Invest in a quality water testing kit and make necessary adjustments to keep your aquarium in top condition.

Feeding and Diet

Killifish have a diverse appetite, making it essential to provide a varied and balanced diet to ensure their health and well-being. In this section, we’ll discuss the types of food you can offer your killifish, including live foods, frozen foods, and dry foods.

Live Foods

Offering live foods is a great way to replicate their natural diet and stimulate their hunting instincts. Some excellent live food options for killifish include:

  • Brine shrimp: Killifish enjoy catching and eating these small aquatic crustaceans.
  • Daphnia: Also known as water fleas, daphnia are another suitable live food source for your fish.
  • Bloodworms: These small larvae are cherished by many fish species, including killifish.
  • Microworms: Tiny worms that can be easily cultivated at home or purchased from a pet store.

Remember, only feed your killifish as much live food as they can consume within a few minutes to avoid overfeeding.

Frozen Foods

Frozen foods can be more convenient than live foods while still providing essential nutrients. Thaw the food before feeding it to your killifish. Some popular frozen food choices are:

  • Frozen brine shrimp: A readily available and convenient alternative to live brine shrimp.
  • Frozen daphnia: Similar to their live counterpart, frozen daphnia offers a nutritious meal for your killifish.
  • Frozen bloodworms: Easy to store and portion, they are a welcomed addition to your fish’s diet.
  • Frozen mysis shrimp: Small, nutrition-packed shrimp that your killifish will eagerly gobble up.

Dry Foods

Incorporating dry foods into your killifish’s diet is beneficial for convenience and variety. There are several types of dry foods to consider:

  • Flake foods: Choose high-quality flakes that contain an adequate amount of proteins and nutrients.
  • Pellets: Opt for small-sized pellets that can fit comfortably in your killifish’s mouth.
  • Freeze-dried foods: These can include ingredients like brine shrimp, tubifex worms, and daphnia. Hydrate them before feeding to your fish.

Make sure to combine different food types to provide a well-rounded diet. By offering a variety of live, frozen, and dry foods, you’ll help ensure your killifish remain healthy and vibrant.

Suitable Tank Mates

While choosing suitable tank mates for your Killifish, consider selecting peaceful and small fish that won’t outcompete or stress your Killifish. Remember, a harmonious environment in your aquarium is essential for the overall well-being of the fish.

Here are some tank mates you can consider for your Killifish:

  • Celestial Pearl Danios
  • Rasboras
  • Small Tetras
  • Dwarf Cichlids
  • Cherry Barbs
  • Dwarf Gouramis
  • Livebearers
  • Snails
  • Shrimp
  • Small Loaches

Providing a comfortable, secure, and stress-free environment is essential. Always care for your fish by maintaining the recommended water parameters, like the ideal pH, temperature, and water hardness. Additionally, ensure there’s plenty of hiding spots and swimming space for your aquarium inhabitants.

Now that you know the appropriate tank mates for your Killifish, you can curate a thriving, diverse, and beautiful aquatic ecosystem for you and your fish to enjoy. Don’t forget to monitor tank conditions and compatibility regularly to ensure a healthy and harmonious environment for all inhabitants.

Breeding Killifish

Hey there! If you’re looking to breed your beautiful Killifish, you’re in the right place. Before diving into the specific breeding methods for the two types of Killifish (Annual and Non-Annual), let’s have a brief introduction to get you familiar with how to breed these stunning fish. Enjoy your journey into the world of breeding Killifish!

Annual Killifish

Annual Killifish have a unique breeding process due to their short lifespan. These fish lay eggs in the substrate, which then undergo a period of dormancy called diapause. Here’s a step-by-step guide on breeding Annual Killifish:

  1. Set up a breeding tank: Make sure you have a separate tank dedicated to breeding. A 10-gallon tank with soft, acidic water, and a sponge filter should do the trick. Temperature should be maintained around 75°F (24°C).
  2. Provide the right substrate: A layer of peat moss on the bottom of the tank makes an ideal breeding ground for Annual Killifish. Keep it moist but not submerged in water.
  3. Introduce the pair: Move a healthy male and female into the breeding tank. Isolate them for a few hours to get them familiar with their new environment.
  4. Feed them well: Offer a high-quality diet, including live food like Daphnia. Feeding them nutritious food helps improve their breeding health.
  5. Check for eggs: After spawning, remove the parents from the tank. Check the peat moss for eggs, which should be amber-colored and slightly larger than grain sand.

Now, the diapause phase starts. Remove the peat moss, keeping it moist, and store it in a dark place for around two months. After this period, return the peat moss to the tank with water and gently stir it. The eggs will hatch within a few hours to a week.

Non-Annual Killifish

Breeding Non-Annual Killifish is a bit different. They usually lay eggs on aquatic plants, and the eggs hatch within a couple of weeks. Here’s what you need to do:

  1. Prepare a breeding tank: Similar to the Annual Killifish, set up a separate breeding tank of about 10-gallons with water parameters suitable for the species.
  2. Add aquatic plants: Non-Annual Killifish prefer laying eggs on plants, especially floating ones like Java Moss. Make sure to include plenty of plant matter in the breeding tank.
  3. Introduce the breeding pair: As with Annuals, move a healthy male and female into the breeding tank and allow them to settle for several hours.
  4. Feed them well: A nutritious diet that includes live food like Daphnia will bring out the best in your breeding pair.
  5. Monitor the spawning process: Non-Annual females will lay eggs on the plants over several days. After they have finished spawning, remove the pair from the breeding tank.

Eggs usually hatch within two weeks. Keep an eye on the breeding tank during this period, and once you see baby fry, provide them with adequate food and care as they grow.

Happy breeding, and don’t forget to have fun along the way!

Health and Disease

In this section, we will discuss common illnesses that may affect your killifish and some preventive measures you can take to keep them healthy.

Common Illnesses

  1. Ich: Also known as white spot disease, ich is a parasitic infection that causes white spots to appear on your fish’s body. Fish infected with ich will be very uncomfortable and may rub against objects in the tank.

To maintain your killifish’s health, it’s essential to keep an eye on their behavior and appearance for any signs of illness.

Preventive Measures

  1. Maintain Optimal Water Parameters: Ensuring that your tank’s water parameters are within the appropriate ranges for your killifish species is crucial for preventing diseases. Keep the water temperature and pH level within the recommended range for your specific species.

  2. Regular Water Changes: Performing regular water changes helps maintain a clean environment for your killifish, which can prevent the spread of diseases and support their overall health.

  3. Use a Good Quality Filter: It’s essential to use a filter suited for your tank’s size and shape, which will help keep the water clean and free from harmful bacteria.

  4. Quarantine New Fish: Before introducing new fish into your killifish community, quarantine them for at least two weeks to ensure they are healthy and free of any potential illnesses.

Remember, keeping your killifish environment clean and well-maintained, and monitoring their behavior can help prevent health issues and ensure a longer, happier life for them!

Killifish Maintenance

In order to keep your Killifish healthy and happy, proper maintenance is crucial. This section will cover two essential aspects of Killifish maintenance: Water Changes and Substrate Cleaning.

Water Changes

Regular water changes are important in maintaining a stable environment for your Killifish. It is recommended to perform a 10% weekly water change or a 25% water change every other week. Make sure to treat tap water with a water conditioner before refilling your aquarium.

When changing the water, remember to:

  • Maintain optimal temperature (72-78°F) with an aquarium heater.
  • Keep the pH level between 6.5 and 7.5, depending on the specific species of Killifish you are keeping.
  • Make sure the water hardness is appropriate for your Killifish species, as some prefer soft water, while others prefer hard water.

Substrate Cleaning

Keeping the substrate clean helps promote a healthy environment for your fish. To clean the substrate, use a siphon vacuum gravel cleaner to effectively remove dirt and debris trapped within the substrate.

Here are some substrate cleaning tips:

  • Make sure to clean the substrate during your regular water changes.
  • Avoid disturbing the Killifish when cleaning the substrate, as they can become stressed.
  • If you have plants in your aquarium, be gentle around their roots to avoid damage.

By diligently maintaining water changes and substrate cleaning, you will be well on your way to providing a healthy and comfortable home for your Killifish. Remember, consistency and attention to detail are key in keeping your aquatic pets happy.

Frequently Asked Questions

What type of tank setup is best for killifish?

For the best environment for your killifish, you should provide a tank with a size and shape that accommodates their natural swimming patterns. The tank should be equipped with a suitable filter and have a substrate that mimics their natural habitat. Keep the water flow low to replicate their natural habitat.

What should I feed my killifish?

Killifish are opportunistic feeders and thrive on a varied diet. You can feed them flakes, pellets, frozen food, and live food. Offering a diverse diet will ensure the health and well-being of your killifish.

How often do killifish need to be fed?

You should feed your killifish once or twice a day, providing an amount that they can consume within a few minutes. Overfeeding can lead to poor water quality and health problems for your fish, so be mindful of portions and remove any uneaten food promptly.

What are the ideal water conditions for killifish?

Monitor the water conditions regularly to ensure the optimal environment for your killifish. Maintain a pH balance between 6.0 and 7.0 and a water hardness between 4 and 15 dGH. The water temperature should be kept within the species-specific range, which can typically be found in the care guide for your particular killifish species.

Do killifish get along with other fish species?

Killifish can coexist peacefully with other calm and similarly-sized fish species. However, always research and consider the temperament and specific requirements of the fish species you are considering before adding them to your killifish tank. Some species might have different water parameter requirements or be more aggressive, which would potentially create stress and conflict within the tank.