Ideal Tank Temperature & Conditions for Killifish

Killifish are beautiful and vibrant colored fish that have become a popular choice of many people across the globe. These fish require specific temperature and water conditions that should be maintained for their healthy growth.

What are the ideal tank temperature and conditions for killifish? The list of water conditions includes temperature (72-75 degrees Fahrenheit), pH (6-7) and water hardness (120-160 parts per million).

Since Killifish have a robust nature, they will adapt well in new settings, but it is preferred that you create a home for them that is similar to the one they have in the wild. Remember that this fish is not demanding, and you can easily replicate their natural home.

Setting up your Tank for Killifish

The Killifish usually grow up to 2 or 3 inches. For this size of fish, you can easily keep a single pair in a 20-gallon tank. However, the larger species grow up to 6 inches and you will need a larger tank for them.

The Killifish are also called the aquatic gymnasts as they jump out of the water. Therefore, a killifish owner needs to ensure that the tank is properly fitted in order to prevent the fish from jumping out and falling on the floor.

Try to reduce the water movement in the tank and purchase a long and shallow tank for your precious Killifish. This is so because the killies live in shallow waters in the wild and they will like to live in a shallow tank.

Add some rocks and floating plants in the tank to replicate their natural cave-like habitat. The floating plants will provide the fish some shading, and the dark-colored gravel and rock will serve as good hiding places. You can also create additional hiding spots with the help of the roots of plants, wood, and rocks.

In their natural habitat, the killifish inhabit forest streams and receive less sunlight due to the overhanging branches. Therefore, killifish will thrive well in a home where there is a low level of light. Try to add plants that do not need a lot of sunlight. A good choice can be the cryptocorynes. They thrive well, even under a low level of light.

As long as you follow the above guidelines, you will have no problem in creating a suitable and enjoyable home for your killies. But try not to overdo it. Putting in too many objects in the aquarium can eat up space in the aquarium, leaving less room for the fish to swim freely.


The killifish are found in areas of Africa where the temperature is high, and the sun is scorching hot. In the wild, the killifish are adapted to high temperatures, so it is best if a similar temperature is replicated in tanks and aquariums.

Maintain a temperature between the range of 72- and 75-degrees Fahrenheit. This is the ideal range for killies. You can heat up the tank with the help of conventional aquarium heaters which are easily available in the market.

But there is one thing you need to consider. The killies are jumpers and will occasionally jump out of the aquarium. Therefore, you need to tightly cover the aquarium. But the problem arises when you have to accommodate heater cables through the aquarium covers.

However, there is one way. If you are a serious killie-keeper and want to keep a lot of killifish in different aquariums, you can set up different small tanks and heat up the entire room. This way, you don’t have to go through the trouble of heating up every single aquarium individually.


Pure water has a neutral pH of 7. When the pH drops below the number 7, the water becomes acidic. Generally, killies prefer slightly acidic water. The ideal pH range is between 6 and 7.

The level of acidity is specific to different killies. But generally, the killifish prefers to live in slightly acidic water. You can make the water acidic by adding sodium biphosphate (NaH2PO4). This is a weak acid and it will slightly lower the pH level of water.

However, this change in pH is temporary and will not persist. You need to use peat moss to make the acidic change permanent. Simply filter the water through peat moss and you will end up with an acidic solution.

Boil the peat moss and rinse it. Then place it in a box filter that is layered with filter wool. Do not move the box for the next two days. Later on, you will notice that the water has changed color to slight yellowish orange and become slightly acidic which is perfect for killifish.

You can measure the pH of water in the tank using different instruments available in the market. The best option is the aquarium test kits. In order to measure the pH of the water in the tank, do not add anything in the entire fish aquarium.

Simply take a sample of that water and add a drop of testing solution in it. This will change the color of the water sample. Once you see the final color, match it with the color card that comes with the kit. You can easily find out the pH level with the help of this comparison.

Water Hardness

Water hardness refers to the amount of calcium and magnesium salts dissolved in water. The killifish prefer a value between 120 and 160 parts per million. However, it is not mandatory to take care of this parameter. The more important parameters are pH and temperature of the water.

Still, you can check the level of hardness with the help of strip tests. These strips are easily available in the market. However, if you have trouble finding them, ask from a local pet store.

To start off the procedure, take a sample of water from the aquarium. Do not dip the strips in the entire tank itself. Now, observe as the strip changes color. Finally, compare this color with the color chart that comes with the strip test kit. This is an easy and sure shot way of finding the level of water hardness.

Aeration and Filtration

Aeration and filtration hold grave importance when it comes to fishkeeping. The killies live in small tanks and less water accumulates dirt and waste quickly. So, you need to have some system to clean your tanks. Otherwise, the toxic wastes including ammonia and nitrates can be harmful to the health of your killifish.

The process of aeration will help break down waste such as ammonia and nitrites to nitrates, which are far less harmful than the former waste products. You can use an air driven filter to provide aeration in the tank.

As far as the filters are concerned, there are a lot of choices to go through. However, the killifish live in small tanks and the best choice for these tanks is the simple box filters that contain wool. Nothing too fancy and they perform filtration efficiently.

These filters have a large surface area and prove useful in capturing most of the waste and bacteria from the water. Box filters can also trap small fry swimming in the tank. An alternate for this is to use sponge filters.


The killifish are colorful fish that fascinate a lot of people. It is quite easy to keep them in aquariums at home. But you need to take care of the tank and water conditions if you want your fish to live a long and healthy life. A regular pair of killifish needs at least a 20-gallon tank with low levels of light, floating plants, rock, and gravel. They need a temperature of 72 to 75 degrees Fahrenheit and a pH value ranging from 6 to 7. The level of water hardness needs to be kept between 120 and 150 parts per million. As long as you follow these guidelines, you will see that your killifish lives a healthy and happy life.

Related Questions

What can I feed my Killifish? Carnivorous by nature, killies like to eat worms, insects, larvae, crickets, and crustaceans. Just like any other animal, they prefer to eat live food over frozen or dried food. Therefore, prepare yourself to feed your killies live food every now and then.

Feeding your pet is an important task, and you need to feed it properly to maintain its nutritional requirements. Especially, during the breeding season, you need to take extra care while feeding fish. This will help the fish breed successfully.

Who are potential tank mates for my Killifish? The killies are calm and peaceful most of the time. Only when the time comes to select their partner, the males begin to show aggressive nature and fight among themselves to get superiority over the others.

Other than that, they are peaceful. You can keep rummy nose tetra and neon tetra with killies because all three prefer similar water conditions. Before you mix different species, research the fish you intend to add in your tank.

What do I need to know about breeding Killifish? Killifish lay eggs and eat them as well. So, you need to take care of the eggs and the fry. Before the fish eats the eggs, you need to take them out and put them in a separate container.

Give them around 2 weeks and the fry will develop soon. In order to keep them in the same environment as the parents, you can attach a separate container in the aquarium. This will allow the eggs to be at the same temperature and reduce your hassle as well.


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