How Many Killifish per Gallon?

You must have seen the small and colorful fish in aquariums quite a few times. These are killifish. If you want to set up an aquarium in a small space, these would be the perfect option. However, you might be confused with how many killifish you can keep in the aquarium. Let us help you out with this.

How many killifish should be kept in a gallon of water?  If you are setting up species tank; you can keep a trio that is two females and one male in a tank with 5 to 10 gallons of water. If a community set up is what you have in mind; 20-gallon tank is the minimum requirement.

Let us provide you with a brief insight into the care and housing that needs to be provided to killifish.

Housing of killifish

Killifish are just 5 to 6cm long and very easy to take care and breed. Thus, this species is among the first choices for those who do not have any prior experience of taking care of an aquarium.

Number of killifish kept in a tank

This depends on your level of interest in breeding the fish. If you want to set up a species tank; an aquarium of approximately 5 to 20 gallons will be sufficient for the three fish. Two among these here fish should be female.

However, for community setups, larger tanks with a capacity of 20 gallons or more will be required. If you want to keep more males in the tank for breeding, you will have to increase the size of the tank.

One thing you have to keep in mind is that killifish are quite enthusiastic jumpers. Thus, the aquarium needs to be equipped with a tight-fitting lid. This will prevent them from launching out of the aquarium, which they can do even via a tiny gap.

Shallow and long tanks which do not have much water movement prove to be perfect for killifish.

Tank conditions

It is advisable to fill the water up to 70% of the tank. The temperature of the water needs to be maintained between 68° and 75° F. The ph. Range should be within the range of 6.6 and 7.2. The hardness of water should be between 120 and 160 ppm.

Most killifish tend to prefer low-lighting tanks. It is a good idea to fill your tank with lots of plants, particularly floating ones.

Waste products tend to fill small tanks in a short span. Therefore, you will need a filter for the tank. Another option is to change water frequently.

Are killifish aggressive?

Killifish are peaceful species that do not pose much difficulty when kept in a community tank. They get along quite well.

However, problems arise when multiple males are kept in a single tank. This is because males can get aggressive towards each other. Males like to mark their territory or view other males as competition.

Therefore, if you do not have much experience in fish-keeping, it is a good idea to start with just a single pair. Once you have gained experience, you can opt for a group. But make sure that the tank has plenty of hiding spaces in this case.

Another option that you have is to have one male killifish in each aquarium. Male species of other fish that look similar should also be avoided. There is no restriction on the number of females that can be kept together.

You can keep them in the same tank as other small species, provided they are peaceful. Neon tetras are a good option.

What should I feed the killifish?

These fish are mostly carnivores. Thus, insect larvae and worms form their primary diet. However, some fish are omnivores who like to feed on algae.

Most killifish in an aquarium prefer to feed on live foods. Therefore, if you do not think that you can provide them with this diet; perhaps you want to look at different species.

If you want to breed killifish, it is essential to keep the diet well-balanced. The nutritional requirement of the fish needs to be met.

Some of the live food options suitable for the killifish include:

  • Brine shrimp
  • Daphnia
  • Mosquito larvae
  • Tubifex Worms
  • Black worms
  • White Worms

Paste foods, fruit flies and beef heart are also some options that you can try. Try to make sure that you provide them with a diverse diet. Too much of one item would not do them any good.

Newly hatched killifish feed on vinegar eels, micro-worms, and grindal worms.

Related questions

How do I differentiate between male and female killifish? Killifish have varying appearances depending on the species. However, all of them are brightly-colored with vivid patterns on their body.

The heads of most killifish are flattened at the top. Their mouth is present at the top of their face. Teeth are long, pointed and curved. They have round scales and are slender.

Males are brighter as compared to females. All killifish have a dorsal fin in the back half of the body.

Sexing killifish becomes vital if you want breeding to occur or want to set up a community. The dorsal and anal fins of males are larger.

Is breeding killifish difficult? Breeding killifish can be tricky. If you want to breed killifish, you should know that there are two types of reproductive killifish.

Annual killifish: These fish become sexually mature at an early age, within a few weeks. You will need to keep them in a small breeding tank with sand so they can bury their eggs.

After the egg is laid, remove the water and parents and leave the egg warm and moist for three months. Add water again, and the egg would hatch

Non-annual Killifish: The eggs of these fish incubate in water. These fish have to be provided with a barer tank if the tank comprises plants; ensure that parents are removed after eggs are laid. Parents can otherwise eat the eggs.

Non-annual killifish grow slowly as compared to annual killifish.


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