Killifish full care Guide: Tank, Diet

Killifish are one of the most vibrant-colored and beautifully patterned freshwater fish. For this reason, the killifish is a more demanded group of fish for most aquarists.

Care Level:Easy – Difficult (species dependent).
Temperament:Most species are peaceful.
Color Form:Vividly colored.
Lifespan:3 months – 5 years. (species dependent).
Size:2 – 9 cm.
Minimum Tank Size:20 Gallons per pair.
Tank Set-Up:Very simple; bare floor, minimal light, sponge filter.
Compatibility:Community safe with caution (species dependent).

Overview of Killifish

Cyprinodontiformes are commonly known as killifish. The killifish family is a very diversified fish family that compromise of over 1250 species.

Those species are classified into ten different groups. They have adapted to live in a variety of habitats.

They are found on almost every continent across the world, except Australia and Antarctica.

They are mainly found in shallow tropical and subtropical waters. They are mostly freshwater fish but some of the spices are saltwater.

They are found in both still and moving water. Some killifish (Annual Killies) have a life span that only lasts for a few months.

The vast majority of killifish can grow up to one or two inches, the larger species can grow up to six inches.

Appearance of killifish


The males are much brighter than the females, and most killifish heads are flat at the top.

The majority of killifish species have round scales and no barbles. Most Killifish are slender and pike-shaped, which makes them great swimmers.

The body size and shape vary depending on the species. They all have a dorsal fin set towards the back half of their body.

In most species, males have large dorsal and anal fins. There are some smaller species of Killifish including The Dwarf Medaka and The Hummingbird Lampeye are less than one inch.

Behavior and Compatibility of Killifish

They are peaceful and get along well in community tanks. The males can be aggressive toward each other.

If you are a beginner then it is recommended you keep a pair of killies in the species-only tank.

If you are experienced and want to keep a group of killies in a large tank then you can do so as long as you gave them plenty of hiding spaces.

They are usually good community fish and can be kept with other small and peaceful species that require similar water conditions, such as Neon Tetras and Rummy Nose Tetras.

Also, keep in mind they are incredibly good jumpers. So make sure you carefully cover your tank during tank setup.

Tank Requirements of Killifish

The tank size and setup will depend on how many fish you want to keep and what is your reasons for keeping them. Whether you keep your killies in saltwater or freshwater will also depend on the species.

Tank Setup

A 20-gallon tank is perfect for a regular pair of killies. If you want to make a community tank then adjust your tank accordingly.

The tank should be long and shallow with very little or no water movement. Make sure your aquarium has plenty of live plants, mainly floating plants.

They should be maintained at a low level. Use plants that are suitable in low light including Cryptocoryne.

You can leave the floor empty, but most people like to cover it with dark gravel. If you choose to use gravel, you should choose a type of gravel that will not harden the water.

You should also make some hiding places for your fish. This can be the roots of floating plants, wood, or rock.

Tank Conditions

The water condition of your tank depends on the species of killifish which will inhabit the tank. The water temperature should between 72 – 75oF.

The pH balance is different in each killifish tank because they have different preferences for each. For example, some come from soft acid water and others come from hard alkaline waters.

Water hardness of 120-160 ppm is appropriate for this fish.

The lighting also depends on the species of killies. Most killies are used to shading from direct sunlight and so they prefer low lighting.

The water movement should be low or no movement at all.

Small tanks are much easier to pollute than larger ones, as the waste products build up quickly.

If you have a small tank then use a simple box filter with a filter sponge or filter wool. For large aquariums, you might choose to use under-gravel filters.

Diet for Killifish

They are mostly carnivores, and they eat crustaceans, insect larvae, and worms. Some are omnivores and include algae in their diet.

In an aquarium, Most killies require live food. The best suitable foods for adult killies includes:

  • Brine Shrimp.
  • Daphnia.
  • Tubifex Worms.
  • Black Worms.
  • White Worms.

Hey, I am Shuvradeb Biswas a content writer. Fishkeeping is my hobby. There are many problems I faced during my first fishkeeping. So, I made the blog to help new fishkeepers.

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