Killifish – Appearance, Species, Breeding, Tank Requirements, Diet

Killifish are famous as pet fish among fish tank owners. In this article, we have added everything you should know before keeping a Killifish in your aquarium.

Everything About Killifish

Killifish are oviparous, and they have more than 1200 species around the world. They are eye captivating and best for aquarium life. It is a famous fish and has a wide variety of colors, sizes, and shapes. 

Killifish Habitat 

The subtropical waters are the habitat for killifish, and they are also present in tropical environments. They change their habitats based on their requirements for daily life. The survival of the killifish in the small pools, streams, and swamps is worth watching.

They love plants around them, and that is why most of them chose to move around them. The light and the moderate temperature is essential for these species. They make such places their permanent habitat where these sources are in abundance. 

Killifish water requirements

They like to live in acidic water, and that’s why most of them have these tiny colored spots on their bodies. Local water or tap water is also suitable for them.

The breeding increases in the water of 7 pHs. An aquarium with multiple filters is convenient for their survival. The fish houses with water heaters increase the life span and health of the killifish. Always use tap water with filtration, or it causes serious hazards. 

Behavioral activities

Some people prefer to keep them in mega fish houses, but few people place to fish in home aquariums. They are tiny creatures and show peaceful behavior. The male species are furious, and they fight with each other.

The male fight is also a rare phenomenon, and they remain calm mostly. Few types of killifish are aggressive. Keep those types alone and away from each other. Always take proper instructions before buying any of these species.

Killifish Diet

These are carnivores naturally; they depend on the meat and other such components. They eat all types of shrimp, and the quantity of food depends on the fish’s size.

A big fish take three to four meals daily. You can buy frozen shrimps and place them inside the water tank. The newly hatched shrimps are one of the favorite items for them.

They also eat other insects that get inside the aquarium. Killifish do not like fruits in ripe or dry form. They eat and consume food in less than two to three minutes. It is a complete system of instantly chewing and swallowing. 

Food items for Killifish

  • Mosquitoes: They are available in ponds and water areas. They are available in specific seasons and killifish like them a lot. Cultured mosquitoes are also available in commercial packaging. 
  • Black worms: These are available online and in other fish stores. They are highly nutritious and healthy in their life. They are fantastic in a moderate amount, or they cause diseases.
  • White worms: They are valuable in their nutrition pattern. They have multiple fatty acids inside them that are helpful for a protein source. 
  • Shrimps of all kinds: Killifish casually consume them, and they provide excellent nutrients. 

Which food item killifish never like to eat?

They depend on all types of meat, and they like it excessively. All the killifish abandon the dry fruits, either they are seeds or ripe fruits.

It does not like vegetables and other plants. They can live on them as their habitat but never prefer to eat them as food. 

Killifish Features

They have flat heads and slender bodies. The shapes are cylindrical, and they have teeth inside the mouth. The teeth help in fleshing of all types of meat and meat sources. There are multiple scales on their bodies, and they are round in shape.

The short fins make them rare and costly, and they are appealing due to their vibrant flashing colors and beautiful skin, and the fish add to the beauty of the aquariums. It makes the ordinary aquarium’s eye captivating for the viewers. 

Species of Killifish

The types of killifish vary in terms of the areas and regions. There is a vast range of these species. Some of them are as follow, 

  • Bluefin Notho killifish
  • Chocolate Lyretail
  • Bivittatum
  • Limeatus
Species of killifish Features
Nothobranchius rubripinnis These are fish of tropical aquariums. They live in pairs and grow in the sweet water. Mostly two males live together, and for breeding, they choose other species.

These are colorful and appealing, and they are always available in small sizes. It is a marine species and is found there in abundance.

Aphyosemion bivittatum They are colorful and have multiple scales all over their skin. The colors are orange, blue, and green, and that makes them appealing. They are rare and costly in some cases. The community lives in tropical waters.

Killifish Sizes 

The determination of the size depends on the maturity age of the killifish. These fish are usually four inches casually.

There are few exceptional cases, and fish measure up to ten inches. In centimeters, they are from 2-3cm. The largest species are up to 15 centimeters. 

The life span of the killifish

The lifespan of these fish is from a few months to 3 years. Some species have a life of nine months to more than a year.

They die after this duration, and they do maturation between three to four weeks of their life. It has a short life duration, but they are good fighters. 

Breeding of killifish

They are into three vital groups that are annual, sub-annual, and non-annual. They breed according to these groups, and it is a fantastic feature. They are selective and never go out of their community.

You cannot see a breed of two mixed species like one quality is of killifish, and the other is of catfish. They choose better conditions for the whole process.

Better health conditions impact the breeding process. A layer of half-boiled eggs at the bottom area makes it easier for the fish. They feel attracted to this space, and the procedure starts instantly. 

How to hatch killifish eggs?

The spawning is different in these fish, and they have layers of eggs. They are in various groups and are known as the top and bottom. Some of them feel difficulty in hatching, and it varies from species to species.

They hatch multiple eggs at once, and it increases their family. The tanks and water quantity affects the whole process. There are annual periods in which killifish spawn.

Fill the tank with two to five gallons of water for the breeding fish. Placing leaves at the bottom of the tank makes the environment comfortable for them. Almonds leaves are one of the best options in such cases, and they have to spread property. 

What size tank does a Killifish need?

They are suitable for all types of aquariums that are smaller in size. Killifish are tiny, and the placement of multiple fish is easy. The putting of three to four fish in five to ten gallons tanks is convenient.

In the large setups, always use big tanks with a massive amount of water. There are fish tanks that comprise twenty gallons of water, and several fish’s life, and survive there.

The large tanks are essential if you are keeping more than one male in the tank. The male species are aggressive, and they require more space for adjustment than the females. 

Can you keep Killifish together?

Keeping the killifish together is not a problem, and they are friendly. The interaction happens among the killifish and increases the food chain in all corners of the tank.

The gender effect this specific setting, and it becomes tricky. Always place male and females fish in different aquariums. Never add multiple males in one fish house, or the aquarium turns into a war zone.

It is dangerous for the life and health of many species in the tank. Keep the female species together, and they live and survive more healthily. There are the least chances of a fight between them. 

Are Killifish aggressive?

All of them are not aggressive, but there is aggression for the food competition. These fish are very peaceful animals, and they find no reason for the fight unless bad things happen.

Some species are not community fish, and they like to live alone. The adjustment of these species with the other ones makes them furious. They put themselves in a state of attack.

What fish can live with Killifish?

The killifish like to live alone in their isolates water tanks. There are chances of togetherness with the other fish like catfish and danios.

The breeding pattern increases in such situations, and few people place them together for this purpose. Although the specie breeds with the same community but the surrounding helps in spawning and birth. It increases the family of a specific species in the most appropriate manner. 

How many killifish in one fish tank?

The approximate size of a killifish is almost two to three inches, and it requires up to three gallons of water to survive. Some aquariums have decorative plants and other such materials that occupy a space. You should trim and replant aquarium plants for better results.

The placement of four killifish in an eight to ten-gallon fish house is a great example. It is a standard calculation, and by using it, you can increase the number of fish. The enhancement of species means the tank must contain extra water. 

Is it hard to keep a killifish?

They live for almost five years in a fish tank. The difficulty of keeping varies from species to species.

They do not require essential protocols and environments, but they need their life basics. In case you are not providing a certain amount of food or the water is not compatible, it is a sign of difficulty. 

Are Killifish predators?

Killifish are small in size, but they are predators inside the aquariums. They are carnivores, and that’s why in the absence of food items, they prey on other communities.

They prefer to eat live food items, but it is not necessary for them. The attraction to live food leads to attacking and killing the other fish and small creatures in the fish house. 


They have faster growth than other fish and their species, and the growth pattern depends on the diet and nutrient supply. They increase their size in the elongated form and reach to 54cm approximately.

The initial size is almost five millimeters, and then it turns into such a big size. They are in demand due to their rapid growth. People choose them at their younger age, and they get a full-grown and adult fish in just 14 days. 

The jump and puddle a lot, and it is their favorite activity. The pudding helps them in digesting their food and keeps the body active and warm. Moreover, it does not remain as it is for a period. 

Do killifish eat baby fish?

 In the shortage of food items and packed tanks, this occurs at an excessive rate. The fish eat their babies, and in this way, they fulfill their food requirements of the day.

Although the process is not so good, and it occurs. Killifish owners must supply enough food so they can stop the procedure. 

Do clown killifish live in normal aquariums?

These are temperature-dependent creations, and they like to live in cold water aquariums. They are peaceful and have the interacting capacity with other tiny fish.

A clown killifish has all the training to behave with the other species in a pack water tank. You can use both acrylic and glass aquariums for killifish.

Do killifish need oxygenation?

Killifish need oxygenation and aeration, and the pet owner highly recommends to keep the tank full of oxygen all the time.

The food affects better in such an environment, and it increases the life span without health issues. 


These are rare and expensive due to their fantastic features and body structure. The growth of the fish is another fact that makes it costly. One rare killifish of a specific pond leads to three hundred dollars approximately.