The Ultimate Killifish Guide – Size, Type, Lifespan, Feeding, Tank mates

“Let’s get these pretty little fish. They will be a beautiful addition to our collection”

My brother whooped while pointing at a pair of fish with vibrant color and unique fins in the market. But wait! I was unaware of their breed that made me think if it is good to get a pet without knowing it completely.

So, I decided to research the complete detail of our new pets which are Killifish. This is a popular breed of fish divided in a large number of species. I am writing down all my knowledge to make a comprehensive guide for all of you.

This guide comprises of several chapters; covering every detailed aspect of this fish with headings. You can either study the whole guide or just read the heading which you seek.

Chapter 1: Introduction to Killfish


They belong to the family of Cyprinodontidae which are egg laying fish and are a distant relative of live bearing fish such as swordtails and platies. This fish is also known by the name of ‘egg-laying topminnow’. There are a large number of species of killifish ranging from small to big size with majestic body colors

The name “killi” sounds like it is derived from ‘kill’ or indicates danger but it is not the meaning behind it. ‘Killy’ is a Dutch word that means the ditch of channel. The different species are usually known by their scientific names.

As an aquarium fish, killies are considered as a hardy species but the aquarium bred fish can adjust in various water conditions. Before getting killies, you should have prior experience of at least 2 years so you can take care of this fish in the best manner.

Where can you find killies?

The killifish is a widely spread and diverse group of fish. Most of the time killifish reside near hanging shrubs and trees which institute dim light and cool temperature. They are adapted to survive under an extended range of different natural territories. They are found habitually in shallow sub-tropical & tropical water of every continent except Antarctica and Australia. Different species can be found in both moving and still water. The possible territories of various killifish are the following:

  • Freshwater: Most of the killifish species live in freshwater pools, creeks, shallow streams, and lakes.
  • Brackish water: Some of the species from this family are also found in brackish or salty water.
  • Hot water: Some of the species are found in desert pools where the water temperature can exceed 90°F.

The lifespan of killifish

The lifespan of killies is lesser than other aquarium fish. However, they can live from 3months- 5years in an aquarium.


Killifish is known as one of the most exquisite water creatures. It comes in a variety of vibrant colors and distinctively drawn body pattern. The charm of its beauty attracts many aquarists to keep it in their aquarium.

Body structure

Killifish comes in various appearances due to the wide range of species. The top area of the head of these fish is usually flat. The mouth is located the face tip or beneath it and their teeth are curved, pointed and long. All species of killies lack barbels and poses round scales on their bodies. They have a slim and pike-shaped body that makes them excellent swimmers.

The body shape of killifish depends on the species but all of them possess a dorsal fin that is pointed towards the back of their bodies. Some of them have a cylindrical and long body and many have broad and long fins.

Size of killifish

Majority species of killifish are 1-4 inches in length but some larger species may grow up to 6 inches. There are some smaller species of killifish which are lesser than 1 inch in length. The examples of smaller killies are listed below:

•    The hummingbird Lampeye (Poropanchax myers)

•     The dwarf madeka (Oryzias minutillus)

And of course, there are some extremely large species as well. The orestias belongs to the large-sized species of killifish that can grow up to 10.5 inches in length.

Nature of killifish

The killifish have very calm and peaceful nature. They get along with fish from other species very well. But the males can get aggressive towards other fish due to sexual aggression.

If you want to keep the killifish then it is recommended to keep one male with several females in one tank. You can keep killies together in a large number if you can provide them with ideal tank conditions and secure environment with a lot of hiding places. Due to their small size, they can be kept in smaller size tank of 5-10 gallon. It helps in observing them in a clear or better way. Maintain the good filtration system because harmful toxins accumulate faster in the smaller tank and a small sized fish cannot resist against the dirt water for too long.

Killies are schooling fish which means you have to keep them in a form of group. Living alone can stress them. Avoid putting two look-alike males in an aquarium because they can get hostile and fight with each other over the females. Keep as many numbers of females you want, they are not problematic.

Killifish are a good option to add in community tank along with other fish. But keep in mind that the tankmates of killifish must be the same in size and share a similar requirement of water conditions. The good tank mates for killifish are neon tetras and rummy nose tetras.

Jumping characteristic of killifish

The very common habit of killifish is jumping. All species of killifish are skilled jumpers. They make long jumps out of the tank. As they are small in size they can jump through a very small gap too. Make sure that you cover the tank with a lid to avoid any misfortune later.

Chapter 2: Types of Killifish

Killifish is a big family with almost 1270 species which are further divided into various families. Killies from different species have a lot in common but of course, they have some notable variations of body structure, inhabits and feeding nature. Even the fish from the same species are closely related but they look slightly different from each other.

Following are some popular species of killifish:

•    Lampeye killifish

•    Striped panchax

•    Variable lampeye

•    Banded lampeye

•    Blue panchax

•    Delta killifish

•    Desert pupfish

•    Japanese rice fish

1: Lampeye killifish (Aplocheilichthys kingii)

It is commonly found in Central Africa. This is relatively small species and the fish grows till 1-1.5 inches in length. The average life span of an aquarium Lampeye killifish is 3 years. Appearance wise all the killifish species have almost same body shape i.e. slim and long body, dorsal fin at the back half of the body and round scales. The body color ranges in different shades of creamy to light brown that sparkles under good lighting. The eyes of Lampeye killi also shines in the light. It is usually hard to identify the gender of this fish. The fin of male fish is a little bit more pointed than female’s fin.

The other common names of this species are Sobat Lampeye, Lampeye Killi, and African Lampeye.

They are carnivorous which need to be fed several times a day. The ideal food for these fish is small-sized live food or frozen meaty food. They are schooling fish and cannot live happily unless there are 4 fish living in one tank. Due to their friendly and calm nature, they can also be kept with other species of same size and behavior.

2: Striped panchax(Aplocheilus lineatus)

This species is commonly found all over Srilanka and peninsular India. This fish is usually spotted in slow-moving water. In India, these fish are used for the mosquito control as they feed on mosquito larvae. They are also known by the name of Malabar Killi, Stribet Panchax, and Piku.

These fish grow to a maximum length of 4 inches. In an aquarium, these fish can live up to 4 years. The physical appearance of this fish is typical as any other killifish but it has an arched back. The main appealing factor of this fish is its beautiful body color that is copper bronze with shining gold-yellow scale on the sides extending to the fins.

The male fish of this species is larger in size and brighter in color than female and has a pointed anal fin. They can be fed on frozen flakes, meat, and live food.

3: Variable Lampeye (Procatopus similis)

It is extremely beautiful and delicate fish. The average body length is 2.5 inches. The other names for this fish are yellow Lampeye or Nigerian Lampeye. These fish come in a variety of vibrant colors. These fish are hard to keep as they require extra care, best water conditions, and good food. They are found in different regions of Africa. These fish live in fast moving water of streams and rivers.

The average life span of variable Lampeye is 4 years. the body structure is similar to other killies except for the thorn-shaped attachment on the lower area of the gill cover.

4: Banded Lampeye(Aplocheilichthys spilauchen)

The fish from this species has a very subtle yet attractive body color. The body length is short and they reach up to 2.75 inches. The life span of these fish in a home aquarium is 3 -5 years depending on the tank conditions and food. The male fish possess blue cross-shaped stripes on the tail and has more intense body colors than female.

This fish is adapted to live in brackish water. They can survive in fresh water too but not in the best condition. Whereas, they thrive in salty or brackish water. These fish can be kept in a community tank with suitable tank mates. This is a shy fish so choose the tankmates carefully.

5: Blue panchax (Aplocheilus panchax)

The fish from this family come in many lively colors. It is one of the most common fish kept by the aquarists. They have a dozen of other names, some of them are Blue Eye Killifish, orange tail killifish spotted ricefish and Blue Panchax. This fish is commonly found in Asia. They live in lakes, ponds and sometimes in the hot water springs. These fish are also kept to control the mosquito population

They can grow up to 3.7 inches in length and the average lifespan is 5 years. Due to the smaller sized mouth, they can eat the food that fits their mouth but due to a greedy nature, they tend to eat the bigger and harder frozen food as well. These fish are generally easier to keep.

6: Delta killifish (Aphyosemion deltaense)

The magnificent beauty of this fish grants a mesmerizing look to your aquarium. They are found in Africa at the swampy locations alongside various roots, vegetation, and big woods. These are called annual fish because when the dry season arrives in Africa, the water dries up and these fish die. But the eggs of these fish can resist in dryness that ensures the successful breeding and survival of this species. They do not have a long life even in the aquarium. The average life span is 1-2 years. The body structure is like other killies but the fins are well-developed and longer than other fish of killifish. The beautiful structure of fins gives them a very majestic appearance. Due to its beauty, this fish is highly popular among aquarists. Females of this species are considerably shorter in size than male fish. Another trait of these fish is the aggressive nature of male fish due to sexual desires.

7: Desert pupfish (Cyprinodon macularius)

This is small-sized fish that can grow from 2.5 inches to 3 inches in length. They can tolerate a wide range of temperatures and high salinity. However, most species of pupfish are seasonal, living their entire life cycle of only a few short months in a puddle of water that the desert sun will soon dry up. They are naturally found in hot springs where the water temperature exceeds 45°C with brackish concentration. The salt level is six times greater than oceanic water. When the water turns cold during winters the fish becomes hibernate and dig its place at the bottom of its living area. When spring approaches, the water temperature starts rising again and the fish becomes active again. The life span is very short i.e. 1-2 years.

This species is very easy to take care of in a home aquarium. The male fish turn blue during breeding season while the color of female fish remains the same.

8: Japanese Rice Fish (Oryzias latipes)

They are highly popular aquarium fish. They have other common names such as Japanese killifish, Japanese medaka, ricefish, and medaka ricefish. These fish are ‘amphidromous’ that means they can move from fresh to brackish water during a part of their lifecycle.

They are found in different countries like Japan, China, Iran, Turkmenistan, Korea, and Vietnam. They reside among the rice paddies too. These fish commonly travel between fresh and brackish water during their lifetime. So, they are found in both freshwater ponds and oceans. This is a little fish of 1.6 inches with an average lifespan of 4 years. They are primarily omnivore and can be fed on all types of fish food.

Chapter 3: Feeding Killifish

Some types of killifish are carnivores while a few are omnivores. In wild, the carnivorous eat worms, insect larvae and crustaceans while the omnivorous feed on algae and other plants.

While keeping the killifish in a home aquarium, you need to feed them the live food. The artificial fish food is not suitable for killies. If you feed them frozen flake or other artificial food they might eat it but not willingly. You should feed the pet killifish twice or thrice a day for their healthy growth. Eliminate the leftovers when they are done eating.

Ideal food for killifish

For healthy growth and survival of your killifish, it is important to feed them a well-balanced and varied diet of live food. Many people prefer making food at home to meet the diet requirement of their killifish.

Following are some best food options to feed your killifish:

  • Daphnia: It is very common to live food that can be cultivated or found in an aquatic environment like ponds and lakes.  The excessive quantity is not recommended as they act as a laxative. Plus, you cannot rely on them as the only food source.
  • Brine shrimp: An ideal food choice for killifish. It is a great nutritional source and almost all fish enjoy eating them. You can also get frozen brine shrimp available commonly at fish stores.
  • Mosquito Larvae: You can get them seasonally from the ponds or freshwater lakes. You can also culture them at home by leaving the water containers open in which mosquitoes can reproduce. But make sure that you don’t let the breeding cycle complete and take out the larvae before they turn into an adult.
  • Tubifex worms: You can purchase them in frozen form from aquarist store. They are very healthy and nutritious but sometimes they may carry disease which affects the health of your fish. Rinse the food (worms) before adding it into your tank, it will eliminate the risk of spreading disease in your fish.
  • Blackworms: These forms are also like tubifex. They are a great source of nutrition and you can get them easily at fish stores.
  • White worms: That is also a great food source but keep the quantity low as they are fatty in nature.

Other foods which you can feed your killies are a beef heart, paste food, fruit flies and few dry fruits.

Fry food

If you plan to breed the killifish then you need to provide the appropriate amount of healthy food. And, also take care of the food requirement of killifish fry. The newly hatched fry cannot eat the same food as adult killifish. Microworms, vinegar eels, infusoria are an ideal food for fry. You can also grind the adult food or egg yolk in powder form and feed it to the fry.

Consequences of over-feeding

Another thing you need to know is that overfeeding is extremely dangerous. Your fish may get sick when you overfeed them and in the worst case scenario they end up dying.

If you add more than enough food inside the tank and do not remove it later then it would start decaying inside the tank. It increases the toxicity of tank water which has a harmful effect on the fish’s health.

Chapter 4: Breeding Killifish

Despite being oviparous and fairly small in size, the Killifish is an extraordinarily easy-to-keep fish. Especially, when it comes to breeding.
Killifish are not very fussy about their sexual partners or the water conditions during spawning. They are easy-going small sized fish that are highly capable in terms of adjusting and adapting. The females especially are known as ‘egg-laying machines’. Therefore, you must not keep the males and females together in a tank, if you are not ready to collect the eggs yet.
Killies become sexually matured in two months and can lay up to 30 eggs in a day. This egg-laying cycle is either repeated after every 3 months or once a year. For healthy breeding and living, the Killifish should be well-fed and well-cared for.

Breeding tank requirements

Generally, Killifish do well in Nano or desktop aquariums. For most species, a pair or trio can be easily housed in a tank having a water capacity of 5-10 gallons. However, if you wish to keep more than one male or establish a community tank, then a larger tank having a water capacity of at least 20 gallons is recommended. For breeding purposes, the breeding pair of Killifish can be shifted to an even smaller tank. The water capacity of this tank may be as low as 2.5 gallons.

Naturally, Killifish prefer soft acidic water but the captive bred strains have become acclimated to the local water conditions. Therefore, it is important to know what water conditions the fish were bred in before buying them. Most of the species of Killifish do well in a pH ranging from 6.0 to 7.0 and the temperature should be kept between 68°F and 75°F.

The total hardness of water should be somewhere between 7° and 10°, that is 120 ppm-160 ppm. 10% water change is recommended weekly. If a filter is not installed in the aquarium then water should be changed more frequently.

Killifish appreciate a well-planted tank and lowlights. So one can decorate the Killifish tank with:
• Java Moss,
• Cryptocorynes
• Java Fern and other low-light tolerant plants.
Also, the killies are excellent jumpers so the lid of the tank should be kept tightly shut at all times.

Types of Spawners

Killifish belong to the family of Cyprinodontidae, which has about 1250 species. Hence, there are a number of different spawning behaviours exhibited by the Killies.
Some of them prefer spawning in deeper water, some prefer isolation while spawning while some prefer laying eggs near the surface. Generally, these can be classified into two groups:

  • Plant spawners
  • Soil spawners

In order, to encourage your Killies to breed you may have to mimic the natural conditions and must equip the breeding tank appropriately.

The Plant Spawners

The major aquarium varieties of plant spawners include:

  • Aphyosemion
  • Fundulopanchax
  • Aphanius
  • Aplocheilus
  • Epiplatys
  • Pachypanchax etc.

These Killies prefer laying eggs on floating plants. Mopping method, is a common and popular method of breeding the plant spawners. Basically, a mop manufactured from nylon or 100% acrylic is used.

The plant spawners lay their eggs on the strands of the mops. The mop is then placed at the bottom of the tank or is suspended such that it becomes ‘floating’ mop. Killies prefer mops with long strands which reach or lay on the bottom. Though the colour of the mop does not matter much, some hobbyists claim that their killies prefer darker colours (such as dark green).

It is very important to boil the mop before use. Mops made up of wool and cotton should be avoided as they may deteriorate in the water.

After the eggs have been laid, the mop should be removed within two to three days. It should be dried gingerly using an absorbent towel. Next, the mop should be inspected under strong light and tiny, delicate eggs of the Killie should be harvested with great care. They can be picked up by a finger or a tweezer may be used. One should grab the eggs gently from the backside rather than directly grasping it. That’s because the eggs are very delicate and may break.

Newly laid eggs can be a bit soft. If this is the case, they should be placed back in to the breeding tank until they harden (2-3 days) Then the eggs should be transferred to an incubating tray (preferably, of plastic). This tray should be filled with the breeding tank water. It should have a depth of at least 5cm.

If the eggs are cloudy or collapse when touched they should be removed immediately as they are either infertile or dead. Keeping them along with other eggs for a longer time may endanger the healthy eggs. That’s because they are susceptible to bacteria and fungus. Also, as a preventative measure, you can add acriflavine to protect the eggs from fungus.

Sometimes, the eggs may be collected from the mop and stored in a tightly packed jar which is already filled with damp peat. The eggs should be placed at the surface, and you may have to add a small amount of water to the from time to time. This will keep the peat damp. Bad eggs should also be removed as soon as they are identified. This process is called the vaporizing method for the incubation of eggs. It is a time-taking process but the best alternative to the water incubation process.

The Soil Spawners

Soil spawners can be further divided in to two types:
Type 1: It is compulsory to provide the eggs of these Killies with a drying up period during incubation.
Type 2: Their eggs can undergo drying period as well as water incubation.
To encourage these Killies to breed, firstly, you must arrange a plastic bowl that comes with a lid or a drum bowl.
If you opt for a plastic bowl cut a hole in the lid with a diameter of about 5 cm or more, depending on the size of your Killifish. Also, add a small rock to weigh it down.

After that, fill half of the breeding bowl and layer the bottom completely with peat moss. The bottom layer should at least have 1-inch thick. This is because some of the soil spawners, are ‘peat divers’ which means that they prefer laying their eggs deep in the soil.

Make sure you boil the peat moss first. This will sterilise it, remove any germs and will remove the oil from it. Then cool it with running water.

Once you place the peat-moss filled breeding bowl in the tank, some particles of the peat moss may rise to the top. You can remove this floating debris using a fish net.

Sexually matured and healthy fish will begin with the breeding process immediately. Either of the female or male will swim into the breeding bowl, and the other will follow. During mating, the Killifish will remain motionless for a while, after which they will part ways with a jerking movement. The peat-spawners will lay their eggs slightly below the surface. While the peat-divers will lay their eggs deep in the peat.

To collect the eggs, the peat moss should be gently lifted from the breeding bowl and dried. It is important to remove the infertile eggs as they may encourage the growth of bacteria and fungus. The peat should then be sealed in a plastic bag for a period of 3-6 weeks depending on the specie of the Killie. The plastic bag containing the eggs in peat moss should be stored under 70°F – 75°F.

A prominent indication of the fully developed eggs are small black dots on the surface. These dots are basically the eyes of the fry. After this stage, they can be placed in a tray containing water for hatching. Note that, the hatching of Killie eggs is triggered by high temperatures and lack of oxygen. Therefore, a suitable temperature and environment should be provided.

Hygger Titanium Aquarium Heater

To ensure the well-being and comfort of your Killifish, it is important to maintain a stable and appropriate temperature in the tank. For this reason, you need to install a safe and reliable heater in the aquarium such as this Hygger Titanium Aquarium Heater.

This metal aquarium heater is suitable for both saltwater and freshwater fish. It is light weighted and corrosion resistant. It can be installed in medium sized aquariums, ranging from 5-45 gallon.

Sponge Filter

This Aquaneat Air Pump Sponge Filter has a double 10-layer design which provides both mechanical and biological filtration. In addition to that the air infusion chamber produces minute bubbles which in turn increases oxygen solubility. This filter is highly suitable for small sized fish like Guppies, Dwarf Cichlids, Killifish etc and can support a tank of 20 gallons or more. It is extremely easy to clean and set up.

Live Aquarium Plants

Adding fresh aquatic plants to the aquariums enhances the growth of the fish to a great extent. This product consisting of fresh and healthy plants fulfills the very need.

Greenpro Driftwood Decor Plus Live plants is basically a collection of live aquatic plants (including java moss, java fern, anubias etc) and driftwood which enhances the environment of the aquariums and provides the fish with nutrients like cellulose and lignin. These nutrients improve the digestion of the fish.

Chapter 5: Tank Mates and Requirements for Killifish

As a pet, the Killifish does not only add beauty and colors to the tank but also saves much of your time and effort with its highly adaptable and easy-going nature.
The Killifish belongs to a family consisting of 1250 different species. Each species is unique in its own way and has different requirements both in terms of tank conditions and tank mates. In spite of that, surprisingly, the captive bred strains have acclimated to the local water conditions. Here, we have compiled a comprehensive set of requirements so that you may provide these enchanting little creatures with the best of life!

Tank Size

On average, the aquarium varieties of Killifish grow up to a length of 2-2.5 inches. For this reason, the Killifish are usually kept in small aquariums like Nano or desktop aquariums. The water capacity of Nano or desktop aquariums ranges from 2.5 gallons -10 gallons.

Most Killie-keepers prefer keeping the species they have in it’s ‘pure state’. The smaller tanks aid these aquarists in keeping the pairs and trios of the Killifish separate. Hence, preventing the breeding of different species, and the production of hybrids.

However, some species of the Killifish like the Blue Gularis (Fundulopanchax sjoestedti) may grow up 5-6 inches. For these, tanks with a water capacity of 5-10 gallons are more suitable. If you wish to keep a pair or trio of the larger species or want to establish a community tank then, you must arrange a tank that holds 20 gallons (or more). Also, the tank should be completely covered to avoid any unfortunate outcomes. That’s because the Killifish are excellent jumpers, and can jump through the tiniest of gaps.

Water Parameters

For healthy living and development of any fish, it is important to provide it with suitable and stable water conditions. For that, one must take care of the following;
• Temperature
• pH
• Water hardness
• Water filtration

The temperature of the water greatly affects the biochemical reactions occurring in a fish’s body. Therefore, providing a fish with suitable and stable temperature is very essential. The ideal temperature for most species of Killifish ranges from 70°F -75°F. Heaters can be used to regulate the temperature of an aquarium. However, commonly serious Killie-keepers have a room full of tanks. Due to which the need of a heater is eliminated as the temperature of the room is already higher than usual.

Coming from the tropical and sub-tropical waters of Antarctica and Australia, the Killies prefer soft acid water. The most appropriate pH level to be maintained in a Killifish tank should range from 6.0-7.0. Fluctuating pH should be avoided at all costs. It can cause stress over a fish, or in severe cases may even cause death. Also, some of the species prefer alkaline waters, so a thorough research is advised before purchasing a fish.

Water hardness is not as critical as temperature and pH but some Killies thrive well in soft water while some thrive well in hard water. Most Killies prefer water of 120-160 ppm.

Small aquariums are easily polluted as compared to large aquariums. Therefore, it is very important to install a proper filter system in the tank. Otherwise, intolerably high levels of toxic compounds and lack of oxygen may cause the Killifish to suffocate and die. Sponge filters or simple box filters containing filter wool are most appropriate for small tanks. They filter particulate matter from water. Under-gravel filters may be used in larger aquariums. Also, at least 10% to 25% of the water should be changed on weekly basis.

During the breeding process when substrates like peat moss are added to the tank, one must take immense care. The peat moss acidifies and softens water creating conditions in which velvet (a deadly disease) thrives. As a preventative measure, you can add two tablespoons of salt to the breeding tank.

Tank Decorations

The vividly coloured and beautifully patterned Killifish appreciates a well-planted tank. You can add plants like
• Java Moss,
• Java Fern ,
• cryptocorynes and many more
They will make your tank more comfortable for the Killies and a lot more eye-pleasing.
Plants also help to oxygenate the water and utilize the organic waste produced by the fish. They also play an essential part in the breeding of plant-spawners.
In their natural habitat, Killies are not exposed to direct sunlight. This is why they prefer low-lights in their tank. During breeding, some Killies may require intense light. For that purpose, ceiling lights may be used.

Compatible Tankmates

Generally, the Killifish have a peaceful temperament which makes them compatible with a number of fishes. Killifish do well in a tank full of other similarly sized fish. They can be kept in community tanks with
• Tetras
• Danios
• Rasboras
• Rainbows
• Apistos
• Smaller catfish etc.

However, if you want to breed the Killies, it is advisable to separate the breeding pair from the community tank. Mainly because most species prefer isolation. Secondly, it will also prevent breeding amongst different and will hence prevent the birth of any hybrid.

Due to their territorial nature, the male Killifish can be a bit aggressive towards male of the same species or similar looking males. Therefore, even the mixing of species should be avoided. Aggression between the fishes can lead to fight and bullying, which in turn can cause stress over the fish, deteriorating its health.

The Killifish should not be kept with larger fishes like Goldfish, as they may consider the tiny Killies as snacks and may try to eat them.

Related Questions

Do killifish eat flake food? Some of the Killifish are reluctant to eat dry foods like fish pellets and fish flakes. These can be trained to eat dry food. Others take them in readily. The dry foods provide the Killifish with a balanced amount of nutrients and vitamins are easily available in the market.
However, naturally, Killies prefer live foods like black worms, white worms, fruit flies, tubifex worms etc. Providing your Killie with the food of its choice, will definitely keep your Killie happy and healthy.

Can I keep different species of Killifish together? One can easily keep different species of Killifish together as they have a peaceful temperament. However, keeping two different species together in a tank could lead to infertile offspring or the birth of hybrids. Both of which, are difficult to deal with. Also, the mature male Killies can be a bit aggressive towards each other. Thus, it is unwise to keep two different species of Killifish together.
Are killifish hardy? Yes. The Killifish are extremely hardy as they are capable of adjusting and adapting to a variety of water conditions. Most Killies put up well with slight changes in the environment and will even adapt to the new environment if its kept constant. They do not demand much of your attention and effort. Also, replicating conditions of their natural habitat in your tank setup is not difficult at all.


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