How Many Eggs do Killifish lay?

A killifish is pretty easy to raise and breed. It’s eggs, however, need to be dealt with extreme care.

How many eggs do Killifish lay? Usually, a female killifish lays 30 eggs in a day. The number of eggs laid may vary, depending upon the species, health and size of the Killifish. This cycle occurs either once a year or after every 3 months.

To save you from unfortunate outcomes, here we have gathered every detail that you need to know about the Killifish’s eggs!

About Killifish Eggs

There are two categories of killifish :

  • Annual
  • Non Annual

Annual killies live in temporary water bodies in their natural habitat. While a non-annual killie survives in a permanent water body. Annual killifish die with the evaporation of water and hence require a substrate like sand or peat to bury their eggs in.

The non-annual killifish lives a long life in permanent water bodies and simply lays its eggs like any other fish.

The number of eggs and the frequency of breeding varies greatly with the health of the killifish and its surroundings. On an average, killifish lays 24 to 30 eggs in a day. After this particular time period, you will end up with many eggs in the breeding tank or breeding bowl. This cycle repeats after every 3 months or once a year.

The killifish have a very strange method of laying eggs. Once the eggs are fertilized by the male, they remain attached to the female’s belly. When the time comes, the female moves along the plants detaching the eggs which upon contact, stick to the leaves.

Although, facilitating the fish with plants for healthy reproduction is an important step, but sometimes the eggs can become troublesome to remove if your tank has very fine plants. Slight mishandling while removing can crush the eggs as they are fragile. Also, there is a high risk of parents eating them even before they hatch! So, a breeder must have a cautious eye when killifish start reproducing.


For successful breeding, you must arrange a well-equipped breeding tank for the killies. They should be well-fed with high-quality frozen and live foods like brine shrimps, black worms etc.

To begin with the process, the basic requirements are:

  • A breeding tank having a water capacity of about 2.5 to 5.5 gallons.
  • A healthy and sexually matured breeding pair of Killifish
  • A material that substitutes as pool substrate; preferably peat moss.
  • A suitable plastic container or drum bowl, having a lid or a hole (large enough for the fish to enter and leave)

Firstly, if you are using a breeding bowl/container, then the base of this breeding bowl should be covered with peat moss. The peat moss should be boiled for five to six minutes and then dried completely. This ensures that all the excess acidity in peat is extracted out. The breeding container should be three times as deep as the total size of fish.
The bottom-spawners or “peat divers” prefer a layer of peat that is at least 1-2 inches thick. This gives them an illusion of their natural habitat and they bury their eggs in it.

The top spawners or “peat spawners”, prefer a layer of peat moss that is at least 0.5 to 1 inch thick. They lay their eggs slightly below the surface.

Although a pair of killifish would do fine too, but it’s advisable to place one male and three females in a breeding tank. The females are prolific egg-laying machines and they do not fuss about their sexual partners or water conditions during spawning.

If the fish were not too stressed when transferred to the breeding tank, the spawning will take place almost immediately. Either of the male and female will swim into the breeding bowl or towards the bottom of tank. The other will follow shortly. During the spawning process, both of the Killifish will remain motionless for a moment. After that, they will part with a jerking movement.

Incubating and Hatching eggs

Commonly, the egg-laying duration is 8 hours or so. During this time, the breeders should not be fed or disturbed. Once the female has deposited its eggs, the breeders should be separated from the eggs within 24 hours.
It is necessary to incubate the eggs of a Killifish, otherwise they will not hatch. Peat moss is an excellent material to incubate the eggs.
To start with incubation, you should firstly pour out the contents of the breeding bowl/tank through a fine net. This will help you capture the peat. Then, you can dry up the peat by squeezing it and wrapping it in a newspaper and leaving the bundle at room conditions. If the peat is still wet after 24 hours, repeat the process until you obtain a completely dry mass of peat.
Once it has dried, you can keep it in a plastic bag or Styrofoam box.

This will help to:

  • Keep the temperature constant
  • Protect the peat moss from the attacks of any micro-organisms.

Then, you should wait for the recommended incubation time to pass, to reach to the hatching stage.
Temperature and moisture play a great role on in the incubation of Killifish eggs. The higher the temperature and moisture, the greater the rate of incubation. If you are not ready to take care of the baby fry, then you can keep the eggs in a relatively cool and dry place.
Approximately, the eggs take about 3 weeks to 7 months to fully incubate. The incubation time period depends upon the species. Once the eggs are ready to hatch, eyes of the fry will be clearly visible on the developed eggs.
To hatch the eggs, the peat moss with eggs should be placed in a tray that is filled with water. Water from an established fish tank can be used for this purpose and the depth of water should be at least 5 cm.

You should start with breaking the lumps of the peat moss gently. Most of the peat moss will sink down to the bottom along with the eggs. Some of it may float on the surface. If you wish to remove the floating debris, do it with care as some eggs may be attached to them.
You will be able to see motionless newly-hatched fry within a few hours or at most, in 2 days. They will make wriggling movements initially, but you can shift them to the raising tray/tank as soon as they are swimming freely.

Since the fry are really tiny, you can use an eyedropper or a turkey baster to shift them. Be very careful while shifting them. Mishandling can lead to the breakage of the killie fry’s backbone and cause its death
Also, you can store the peat moss back into a plastic bag for further incubation, as it still may have lots of killie eggs well-protected in it.

Raising the young

It is much suitable to transfer your fry into raising trays away from parents as they usually are able to strive independently.

Also, they do not need processes such as aeration or filtration. Make sure that the water in which you raise your fish is ‘aged’ which means that the water is left outside for a day or two. Also keep on raising the water level as the fry grow. It helps them to adapt to the new environment.

There is no need to cover the trays as baby fry do not jump. It is only when they attain adulthood that they show such behaviour. The baby fry may show sensitivity to temperature so make sure that the tray is not heating up.

Moreover, if you see a layer of oil accumulating at the surface, do not worry as it will not harm the fry. You could, however, try to remove it.

Feeding the killie fry is an easy job.

The feeding requirements are as follows:

  • Till the fry turns 1-week-old, feed it once a day with Artemia, micro-worms or vinegar eels.
  • From 2 weeks onwards, add chopped tubifex worms to their feed. This makes them healthy and increases their growth rate

However, be careful that your fish isn’t overfed as this can lead to death. Frequent water changes should be avoided too. Once your fry turns 3 weeks old, you can transfer it to a proper tank.

Related questions

How to distinguish between male and female killies?There are various ways to differentiate between a male and female killifish like:

  • Males are found in more vibrant colours than females
  • The anal fin of males is more pointed than females which have a rounded anal fin
  • Females are more plump and larger than males

Are killifish difficult to breed? In comparison to breeding requirements of other fish, killifish breeding is very easy. The fish do not require deep tanks or special feeds. They can easily start reproduction in shallow water with a depth of about 6 to 8 inches. Their basic necessity is clean water, preferably acidic with a pH value between 5 to 7. Also, you need to place them in a closed tank because they jump a lot and one surely does not want his killies jumping everywhere.

Are killifish aggressive?Generally, most species of killifish have a peaceful temperament. They do not cause much trouble and easily adjust with similar, small, peaceful species. However, some males are aggressive towards other males. They usually exhibit this behaviour once they mature, and it is more common in bottom-dwelling killies.
Despite their small size, the killifish can get aggressive to such an extent that they can attack other fish and harm them. To avoid such clashes, different species of killies should not be mixed.


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