Can Killifish be Kept in a Community Tank?

We all want our community tanks to look extravagant. And what better way to do this than to add killifish? But the thing is, there are many factors you must take into account before you put these fish with others.

So back to the question, can killifish be kept in a community tank? Most species of killifish are of a peaceful nature and can be kept in a community tank with fish like tetras and rasboras.

Let’s take a look at the community behavior of killifish in detail below.

Should You Keep Killifish in a Community Tank?

Killifish are peaceful swimmers and are usually not aggressive towards other fish. Because of their beautiful colors and patterns, they make a great addition to just about any community tank.

There are over 1200 different species of killifish, each with different shades and colors. Perhaps the most famous species of killifish are the Golden Wonder Killifish, American Flagfish, and the Blue Gularis Killifish. These species are especially timid and are great community fish.

One important thing you should make sure before placing your killifish in a community tank is that the fish are compatible with the water conditions of your tank. These include water temperature, pH and water hardness. Placing different species of fish that prefer the same water conditions will keep all of your fish healthy and stress-free.

Tank Mates for Killifish

Let’s take a look at what types of fish are killies most compatible with. Some great tank mates for killifish include:

  • Rummy nose tetras
  • Rosy tetras
  • Cardinal tetras

You can also choose to keep different species of killifish together. This further reduces the tension between the male killies.

Before placing killies in your community tank, make sure you the others are of the same or slightly larger size. This will make sure that the killies do not bully other smaller ones or cause them stress.

Furthermore, it is important that the other fish you keep are of the same nature as your killies. Ensuring that these rules are followed will have many benefits in the long-run. Not only will they allow your killifish to settle in perfectly, but will also reduce the chances of bullying and fights.

Male Killifish in a Community Tank

If you plan to keep your killifish in a community tank, there is one thing you should know about the males. Most male killifish become territorial if they find another male of the same species in a small environment. Therefore, if you place two males in a small tank, they will very likely fight and end up injuring or even killing each other.

Thus, it is a good idea to get a single pair of a male and female killifish at first if you have a small tank. If you want more killies in your tank, your best bet would be to get two or three females while keeping a single male fish.

But if your plan is to get more male killies, your tank should firstly be large enough to give your fish a place to hide. Along with this, try purchasing male killifish of different species to prevent territorial behavior altogether. What’s interesting is that male killifish are usually more colorful and brighter than the females, so placing different species together will make your tank even more diverse and beautiful.

Water Conditions for Killifish

The water condition of your tank is a huge deciding factor as to what species of killifish you should keep. It also determines if your fish will settle well inside your community tank or not. So what water conditions do killifish demand?

There is one simple guideline you can follow to ensure that your water is perfect for the fish. And that is to bring the water parameters as close to their natural habitat as possible. As there are so many species of killifish with each one of them belonging from different parts of the world, they have different water requirements. Some prefer acidic water, while others prefer alkaline. Some species will be more suited to warmer temperatures while others come from colder waters.

Now, even though killifish are hardy little swimmers, we still recommend you to read a little about the exact parameters for your particular species.

The follwing are the most common water parameters that suit most species of killifish.

At the very basic, the water temperature should be within the range of 72-80°F. Even though some fish originating from hot climates will prefer temperatures as high as 90oF, 72-80°F is a range that most killies would appreciate. A pH of 6.0-7.0 is recommended for the majority of species. Water hardness can be as low as 120ppm and as high as 160ppm again depending on what species of killifish you plan on buying.

Killifish can generally adapt to a number of different water conditions without any effort, although it may affect the incubation period for their eggs.

What do Killifish Eat?

Whether you are going to be keeping your killifish in a community tank or a separate tank, it is of utmost importance to know what to feed them. Killifish are carnivores and their diet mainly consists of insects, larvae, and worms in their natural habitat. Some species of killifish are also known for eating algae.

In an aquarium, killifish prefer live food and sometimes frozen foods. However, these fish are not big fans of flakes and dry food. You should make sure that you can provide these fish with a variety of live food in order to make sure they stay healthy.

Best live foods for killifish include:

  • Brine Shrimp
  • Mosquito Larvae
  • Blackworms
  • Daphnia
  • Fruit Flies

On the other hand, killifish fry favor live food such as newly-hatched brine shrimp and infusoria. Make sure that you never give too much of one food to the adult killifish or their fry.

How do killifish breed?

One of the main reasons why aquarists buy these fish are because of breeding. As these fish are so rare to find, breeding them successfully can be a very rewarding experience.

Killifish basically have two main types of reproductive systems, the annual kind, and the non-annual kind.

Annual Killifish

The natural lifecycle of annual killifish is quite interesting. These fish originate from rivers that become completely dry once every year, killing the fish in the process. Due to this natural occurrence, annual killifish have evolved to reach sexual maturity faster than non-annual fish. These fish have a lifespan of around 2 years in an aquarium.

The way these fish reproduce in their natural habitat has to be replicated in a tank to ensure that they breed successfully. Among annual killifish, there are those that lay their eggs on plants and leaves, while others lay them in the soil. In your tank, you have to provide them with an artificial mop or a substrate that the fish can lay their eggs in.

In their natural habitat, the killifish die after they have laid the eggs due to the drying of the river. In the tank, however, once you are sure that the fish have laid the eggs, you should move them to another tank to avoid the fish from eating them.

The eggs have to be taken out of the water later on and placed on a substrate such as peat moss while they incubate. This process can be as short as 1 to 2 weeks and as long as several months. Once the fry have fully developed, the eggs are placed in the water again after which the hatching begins.

Alternatively, you can let the eggs stay in the substrate after they have been fertilized, then proceed to take out all the fish from the tank and pump out the water from the aquarium as well. Let the eggs incubate in the moist substrate and add water in the tank again once they are about to hatch. This process usually takes 2-3 months.

Non-Annual Killifish

Non-annual killifish are complete opposites of the annual type. Their rivers do not dry up, hence their breeding process is the same as normal fish. They lay their eggs in the water, the incubation of eggs and the birth of fry occurs in the same water. Thanks to this process, non-annual killifish have a longer lifespan of around 3-5 years on average.

The method of reproduction for non-annual killifish in an aquarium is quite simple. As soon as the killifish have laid all their eggs, the adult fish are removed. The eggs then remain in the water as they incubate and hatch. The incubation process in the case of non-annual fish is shorter, at least 2-3 weeks depending on what species you have. Some may take longer, while some shorter.

The eggs of non-annual killifish can be incubated through the same process as that of annual fish. The eggs can be removed from the water and put in a substrate to develop. This, however, lengthens the incubation by some weeks. Still, many hobbyists prefer to incubate their eggs through this method.

Related questions

What tank size is optimal for killifish? Because of their small size, a pair of killifish can very easily be kept in a 15 or 20-gallon tank.

How do you tell the gender of your killifish? Male killifish are much more colorful and vivid than the females. The anal fin of the male fish is pointed and longer, while it is rounder in the case of female fish.

What is the size of a killifish? Most species of killifish are between 1 to 2 inches in size. Some larger species can grow up to 6 inches.


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