How Long can Killifish Eggs Last?

Here’s the deal:

You can either buy live killies or their eggs which you can hatch on your own. And while the latter is a slightly more complex process, it certainly is a lot more fun.

But the question is, how long can killifish eggs last? Killifish eggs can last from a few weeks to a month or two after the embryos have fully developed, under certain conditions.

However, delaying hatching doesn’t come without its consequences. Let’s take a look at these in detail below.

Should You Delay Hatching Killifish Eggs?

Whether you have noticed or not, some people buy killifish eggs instead of living fish. These eggs have to go through incubation and hatch later when the embryo has developed. Most eggs come with a recommended date to hatch the eggs to yield the best results.

However, this can be delayed. Hatching the eggs can be delayed by a few weeks up to 1-2 months. But over here, temperature and climate come into play. These factors can have a huge impact on the yield rate of your eggs.

If you leave your eggs in poor conditions, most of the embryos will die and it will increase the chances of producing belly sliders. Belly sliders are fish that have a swim bladder disorder which causes them to swim abnormally. And this can be caused by delaying the hatching process as well.

Thus, in order to safely hatch the eggs at a later date, it is best to keep them in a slightly colder area while making sure that the peat moss remains humid throughout. Make sure to lower the temperature gradually to avoid harming the embryos.

The main thing is that different species of killifish eggs have different temperature requirements and incubation periods. Thus, it is always beneficial to research a little about the incubation temperatures and overall conditions your species require to produce the best results.

Killifish Breeding

If you start off by hatching your killifish, it will help you in breeding your fish later on. This is one reason why some aquarists prefer to start off with eggs rather than live fish. Let’s take a look at what is the breeding process for killifish.

Killifish are usually freshwater fish that have two different types of reproductive systems:

  • Annual killifish
  • Non-annual killifish

Both these fish lay eggs, but the incubation and hatching process for both are different.

Annual killifish

Annual fish belong to rivers that dry up once in a year. The killies mate and lay eggs in the water, either in the soil or floating plants. Once the rivers dry up, the adult fish die and the eggs incubate. The incubation process is completed just as the rainy season comes and fills the rivers up again just in time to allow the eggs to hatch.

Hatching annual killifish

Hatching annual killifish eggs is a fun and interesting process. The more accurately you follow the steps, the smoother the process and the better the yield will be.

You should begin by selecting a particular species of killifish. This is because each species has different requirements for both eggs and the fish. We will take a general look at killies later on in this article, though it is still a good idea to do some research about your particular species.

Once you have chosen your species, you should begin by looking for eggs. One option is to visit your local pet stores to buy eggs. But because some species are so rare, you would only find them at online auctions.

Incubation of annual killifish

After you have your eggs, it’s time to begin the incubation process. Peat moss is the most common substrate used to incubate killifish eggs. So start by placing peat moss in a plastic or a foam box and then set the eggs on the substrate.

You should then place these eggs in a dark cupboard or any place where the temperature is optimal for incubation and there is least disturbance. The temperature for incubation can range from 20oC-22oC to as high as 29oC depending on your particular species.

Leave the eggs in that condition and avoid moving them unnecessarily. The eggs take several weeks to months to incubate depending on what species you have. Once the embryos have developed, their eyes should be visible. This is an indication that the hatching time is near.

Birth of annual killifish fry

To hatch the eggs, start by wetting the peat with some cold water. Be careful not to add too much water if you’re using less peat moss, as the eggs won’t hatch then. Once you have wet the eggs and peat, take an oxygen tablet, break it into pieces, and place it throughout the water.

These steps mimic natural rainwater. Annual fish are born in a similar habitat where the eggs hatch after the rain fills up the river again. After you have followed all of the above steps, you should notice that the eggs should hatch after a few hours.

Once the swimming fry are visible, you can later use an eye dropper or a turkey baster to shift the fry in a tank. The fry will be tiny and might not be able to swim properly, so wait a while before transferring them to a full-sized tank. Do not use a net to transfer the fish as it can injure or even kill the fragile fry.

Non-annual killifish

Non-annual fish, on the other hand, has the breeding process as that of any other fish. The rivers do not dry up and the eggs incubate and hatch in water. This is one reason why non-annual fish tend to have a longer lifespan than that of annual fish.

Hatching non-annual killifish

Non annual killifish breed just like any other normal fish. They lay their eggs in the water, the eggs incubate within the water and hatch in it too. Thus, the process of hatching eggs is particularly simple for non-annual fish.

We start where the killies have laid all of their eggs. Because the eggs will remain in the water and so will the fish, the adult killies might eat them. And so to avoid this, you will have to separate the adult fish from the eggs while the eggs incubate.

Non-annual killifish eggs can be incubated both with and without water. If you choose to incubate the eggs without water, the incubation process will usually take a few weeks longer than normal.

Once the incubation will be over, the fry will hatch automatically and then you can continue to raise them in another tank.

Raising Killifish Fry

Hatching killifish eggs is a great experience, but you must raise these fry carefully into adults. Killifish fry are quite delicate creatures and just one wrong move can completely wipe out all of your fry. Following are the things you must do after your eggs have hatched.

Separate Tank

Start by preparing a separate raising tank for the fry by putting some aged water and some type of moss like Christmas or Java. Both these moss encourage the growth of infusoria. Infusoria are basically tiny organisms that serve as food for the fry.

You should then move the fry into the raising tank, though make sure that you do not place too many in one tank as it will increase the mortality rate.

Killifish fry Diet and Tank Requirements

Some great foods for killifish fry include:

  • Newly hatched Brine Shrimp
  • Artemia eggs
  • Microworms

Make sure that you are not overfeeding the fry or leaving too much uneaten food in the tank. Bulging bellies are often a good sign of properly fed fry. Feeding your fry once a day is often enough to ensure proper growth.

Usually, water changes are not required for fry as they can injure or even kill them. Killifish fry require aged water only and using any other sort of water such as tap water might kill these fry. You can start changing your water once the fry are at least 3 weeks old. Till then, just keep adding more aged water on top of the present water.

As your fry age, you will need to transfer them to a proper tank. More so, you will have to increase the frequency with which you feed them and mix their diet up a bit. The annual type of killifish is particularly known for reaching sexual maturity quickly.

Once your fish are around 3 to 4 weeks old, you will need to place floating plants and cover their tank with a tight lid. Killifish are famous for being great jumpers, so if you want to avoid finding a dead fish lying on the floor, your best bet would be to make sure that the tank is properly closed.

Related Questions

What is the lifespan of killifish? Killies usually have a lifespan of around 2-5 years. Because annual killifish only live for a year in the wild, they can live up to around 2 years in a tank.

Non-annual killifish, on the other hand, can live up to 5 years in normal tank conditions.

How do you identify the gender of your killifish? A killifish gender can be identified through its anal fins. These fins are pointed and longer in male fish, while they are round in female fish.

Another way to differentiate between these fish is to see their colors. Male killies are often much brighter and colorful than females. Male killifish also tend to have the anal and dorsal fins on the back part of their body, while females have both of these more in the middle.

What water temperature is suitable for killies? Killifish are most comfortable in water temperature in the range of 72-75oF.


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