Killifish are well-loved by many aquarium enthusiasts. This is partially because they make such great beginner fish for newcomers to the hobby.
Since killifish are hardy, it’s easy to care for them and keep them in good shape. A few mistakes generally aren’t going to kill the fish.
Of course, that doesn’t mean that you can ignore the care requirements of the fish. If you keep these fish in an improper environment, they will get sick and potentially die.
The fish tank size is an important thing to focus on when buying killifish. You want the fish to have enough room so you can mitigate any issues with aggression.
Continue reading to learn about ideal killifish tank sizes. You’ll learn about many types of killifish and how big their fish tanks should be to keep them safe.
Best Tank Size for Golden Wonder Killifish
Golden wonder killifish grow to be four inches long at maturity. Since they’re medium-sized fish, they aren’t going to fit in incredibly small tanks.
You’re supposed to keep these fish in 20-gallon fish tanks. This is the minimum acceptable tank size for these fish.
Best Tank Size for Blue Nothos
Blue nothos are another popular type of killifish that’s worth looking into. These are pretty fish that grow to be between 1.9 and 2.4 inches, depending on various factors.
It’s recommended to keep three of these fish in one tank. A 10-gallon aquarium is the minimum acceptable size when keeping these fish.
Best Tank Size for American Flagfish
American flagfish are interesting because they have a pattern that is somewhat like the American flag. They’re popular fish in the US for this reason.
They’re approximately the same size as the blue nothos mentioned above, but they’re much more aggressive. To keep these fish happy, you will do better by keeping three of them in a 15-gallon or 20-gallon fish tank.
Best Tank Size for Clown Killifish
Clown killifish are rather small, and they’re good options for smaller fish tanks. These fish only grow to be between 1.2 and 1.4 inches in captivity.
Often, these fish are kept in groups of three. It’s said that you can easily fit eight pairs in a 10-gallon tank if you’d like to go that route, though.
You can even keep three of these fish in a 2-gallon tank. It’s generally better to go larger than that just so it’d be easy to clean the tank, though.
Best Tank Size for Kisaki Killifish
Kisaki killifish are going to grow to be around 2.5 inches in captivity. Since they’re close to medium-sized, it’s wise to keep them in a 10-gallon tank.
Putting them in a smaller tank might make it tougher for them to grow to full size. Plus, the fish are happier when they have a bit more room to swim around.
Best Tank Size for Red-Striped Killifish
Red-striped killifish aren’t too big, but they’re still going to need space to thrive. You can have a good experience keeping a small group of them in a 10-gallon fish tank.
As always, you want to ensure the comfort of the fish. Fish that are stuck in tanks that are too cramped can easily become stressed.
Best Tank Size for Magnificus Killifish
You want to give the magnificus killifish groups a bit of space to spread out. They don’t do as well if you try to shove them in 10-gallon aquariums.
To have a good experience, you will want to go with a 20-gallon fish tank. This should be appropriate for the fish and will keep them happy.
Best Tank Size for Blue Lyretail
Blue lyretails are neat types of killifish that stand out because of their tails. They only grow to be 2.6 inches in a fish tank, but you still need to give them space.
They do best when you put them in a 20-gallon aquarium. It should be easy to care for the fish so long as you give them enough room.
Best Tank Size for Argentine Pearlfish
The Argentine pearlfish is another aggressive type of fish that some people love. They are rather pretty and can be interesting to keep in your home.
The minimum tank size for these fish is 15 gallons. You need to buy a good 15-gallon aquarium or something larger to accommodate these fish.
Best Tank Size for Blue Gularis
Caring for a blue gularis can be a real treat. This is a showy type of fish that will look great in your aquarium, but it’s a killifish that is recommended for those with a bit of experience caring for fish.
To keep these fish safe, it’s best to put them in a 20-gallon fish tank. They can also thrive in larger tanks if you’d like to go with something bigger.
Best Tank Size for Redtail Notho
The redtail notho is a very peaceful little fish that will grow to be two and a half inches long. These fish are easy to care for, and that makes them rather popular with beginners.
You can keep three of these fish in a 10-gallon fish tank safely. It’s always simple to keep these fish in good shape so long as you’re meeting the basic care needs of the fish.
Best Tank Size for Chocolate Lyretail
Chocolate lyretail fish are rather neat to look at. They have a nice look and good coloration that will appeal to you.
They’ll grow to be somewhere between two and three inches long in the fish tank. These fish have a minimum tank size requirement of 10 gallons, but many say it’s better to go with a 15-gallon aquarium.
Best Tank Size for Two Stripe Lyretail
The two stripe lyretail is similar to the chocolate lyretail mentioned above. However, it has a maximum growth potential of two inches.
This fish should be safe to keep in a 10-gallon fish tank without it being a problem. They’re bright fish that can add a lot of color to your tank if you choose to buy some of them.
How Many Killifish Per Tank
How many killifish you’ll want to put in the tank will depend on the species. Some killifish do fine in large groups, but others do better in small groups.
Know that male killifish like to fight each other. Aggression issues might make it impractical to keep males in the same tank.
Sometimes you can keep males together if there is enough space in the tank. You have to go with larger tanks than the minimum recommendations to achieve this, and it’s not always a guarantee that things will be fine.
Typically, people say that keeping one male killifish and two or three females in the tank will be for the best. This is the standard advice for new killifish owners.
Killifish Minimum Tank Size
The minimum tank size is going to change based on the killifish that you’re looking at. Some types of killifish need to be kept in 20-gallon fish tanks since they’re a bit larger.
Others might be okay in tanks as small as 5 gallons. You must research the tank size that’s recommended for the fish that you want to buy.
Above, you learned the tank size recommendations for many of the most popular killifish. These are likely fish that you’ll be interested in if you’re considering buying killifish for your home aquarium.
Follow the recommendations, and be sure to keep the fish tanks clean. Sometimes it’s better to go with a slightly larger tank than the minimum to make tank maintenance simpler.
Can Killifish Live Alone?
Putting just one killifish in a tank is said to be cruel. These fish need to live with others of their kind to stay healthy and happy.
To get the best results, you should buy one male killifish and two female killifish. This is the minimum number of these fish that will be acceptable in an aquarium.
If you tried to keep a killifish in a tank by itself, it’d become extremely stressed. This will lead to the fish getting sick, and it won’t likely survive for long in your tank.
Keeping at least three of these fish together is the norm. The information you were given above about minimum tank sizes takes this into account.
If you want to keep more killifish together in a tank, you’ll need to buy a bigger aquarium. Aquariums that are 30 gallons or larger will make it possible to keep larger groups together.
Earlier, you learned that males are aggressive toward each other. Larger tanks might make it possible to keep more than one male in the tank.
There should always be more females in the tank than males, though. Many people like to keep twelve or more killifish together in a tank so they can watch them school.
You have a lot more information about killifish and what tank sizes you’ll need for them now. Some killifish do best in tanks that offer 20 gallons of space, but others can thrive in smaller tanks.
It just depends on the species of the fish. You can’t generalize all types of killifish since they grow to be different sizes and have slightly different care requirements.
Pick out your favorite type of killifish and then have fun caring for them. They truly are great fish that will be great additions to your home aquarium.
Jeff has always enjoyed having pets, but as a child, he was drawn to his family’s fish tank. Being able to maintain a small ecosystem and observe the behaviors and interactions in the underwater world peaked his interest early on and has kept him hooked until this day. On Avid Aquarist, Jeff shares everything he’s learned about helping aquatic life survive and thrive in a home aquarium.