Killifish; Caring for the Eggs

Caring for killifish eggs is one of the more tedious tasks involved with these fishes. There are a number of tricks and several rather diverse methods of incubation. We will share a couple of methods we use in taking care of eggs. Both Mop Spawned harvesting and Peat Spawned harvesting are discussed on this page.

Mop Spawning Killies

Proper egg care starts with the harvesting of the eggs.
Wash your hands! Don't use soap, but put a little more effort into the process than simply rinsing. Start with clean containers, clean water and if you chose to use any tools, they should be cleaned also.

We use a anti-fungicide (Acriflavin) in the water we use to store eggs in. We prepare the water before we start collecting eggs. We use an eyedropper and after we take some of the Acriflavin up into the eyedropper and squirt it all back into the container, we rinse the eyedropper into a quart of clean water and it is that water (which should be tinted a faint yellow if you use Acriflavin) which we use to store the eggs. We put about an inch of the water into small plastic cocktail cups in preparation of the eggs hunt.

We remove the mop from the breeding box and check to make sure that the pair is in the water and not in the mop. Sometimes one or both of the fish will stay in the mop as we take the mop from the water...it is important to keep the fish in the water, especially for this next step...we then squeeze the mop...now you get it...we don't want to squeeze the mop with the fish in it (the fish hate it). After we squeeze the mop we wrap in several layers of paper toweling and set it aside for 10-15 minutes.

When the mop is damp (we don't let it dry out) we unwrap it and start to look for eggs. With some pairs, seeing the eggs is very easy. Other pairs challenge you to find their eggs. Some fish lay primarily in the top portion, some the bottom. Some lay in groups of eggs, some scatter them all through the mop. You will have to find which "style" your fish choose and focus your efforts on that part of the mop.

When you find an egg, gently remove it from the yarn with your fingers. Eggs which are very fresh may pop between your fingers. If the first couple of eggs you attempt to lift from the mop pop, put the mop back into the water and wait a couple of hours. Then re-dry the mop and start again. Apparently the eggs are rather soft for the first couple of hours after they are laid. When you have the eggs between your finger, put the eggs in the cup of water and kinda roll it off into the water. When you are done harvesting the eggs...label the cup. You will forget what is in it if you don't...I know you think you won't...trust me on this issue. You will find it helpful to put the name of the fish and the date of the harvest on the cup...not the lid. The lid may be set next to another lid and...well it gets hectic and confusing sometimes.

If you put too many eggs into a cup you may find (like we did) that the tendency to fungus increases. When one egg funguses, there are usually more to follow and when the eggs are crammed into a cup, the likelihood of spreading fungus increases. We also found that covering the cups is not a bad idea, but covering them air tight and putting too many eggs into the cups is extremely risky and is generally a bad thing to do. We use a cocktail cup and cover system that is used for sauces from fast food places. The lids snap on and are not air tight but they do cut down on the evaporation.

On the second day we check the cup for fungused, infertile or dead eggs (white ones and furry ones) and we remove those with an eye dropper. On the third day the water is changed. We use treated water for the water change. Some people chose to use clean water for all water changes.

Changing the water becomes an easy process with just a little practice. We gently swirl the eggs in the cup and set the cup down for a minute or two. The good eggs drift to the center and the bad eggs, which are generally lighter than the healthy eggs continue to swirl around...decant the water and the bad eggs into a second container. The second container is to give some protection just in case a good egg is decanted by mistake. When the water is decanted, pour about an inch of the Acriflavin tinted water into the cup. Check for fungused eggs daily and remove them as they are found.

At the end of a week, change the water again. This time, instead of using treated water, use clean water without fungicide. Any benefit of using a fungicide is probably exhausted in the first week and the chances of hardening the shell of the egg may be an issue to be concerned about.

Check the eggs daily and keep the cups filled with water. The eggs don't do too well if you let the cups dry out. If you have covered the cups like we are suggesting, you will not have too many problems trying to hatch crispy eggs.

Remember that the eggs are living organisms. They should be kept at the proper temperature and out of bright lights. You don't have to keep them dark and they don't have to be 80 degrees...room temperature and out of direct light usually works. If you don't know the ideal temperature for incubation a particular species...try 75 degrees and see what happens.

The length of time it takes to hatch varies between the various killifish. Some may take only a week or so...others take several weeks. Temperature has a lot to do with the time it takes. We consider 2 weeks to be about average and use that as a target when working with a new fish.

If you are having trouble hatching a batch of eggs or if it seems to be taking too long...email us and we will walk you though the process and talk it out with you.
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Peat Spawning Killies

We take a small handful of boiled peat or coconut fiber (we prefer the coconut fiber) and put it in the bottom of a 1 gallon drum. The depth is about an inch. We place a floating mop in the tank for protection and the pair of fish. We harvest the peat each week.

Well...that's the quick description. You probably want to know a little more.

We don't "boil" peat moss. We use a microwave. Heating the peat serves a couple of purposes. The stuff will now sink and some of the organisms have been killed. With coconut fiber, we simply break off an appropriate sized chunk and soak it for several hours. We don't both to boil the coconut and it sinks after just a couple of hours of soaking.

Sometimes we use a small cup in the tank rather than covering the bottom. For most soil spawners, either way works. If you use a small cup you might want to use a marble or two or a couple of small pebbles to keep the cup on the bottom of the tank. Using a cup is an easy way to see if there has been any activity. The fish throw the peat/coconut all over the tank when they are breeding. If your cup is containing less peat and the bottom of the tank is becoming a peat bog (less messy if you use coconut), the chances are that your fish have been spawning.

Harvesting is rather easy. Pour the peat/coconut into a fine meshed net (not a brine shrimp net but the next one up). Gently squeeze the peat/coconut filled net to remove the bulk of the water and spread the peat onto a paper towel. We use a section of the newspaper covered with 4 layers of paper towel. When using coconut fiber, simply squeezing seems to dry the material enough and we don't feel compelled to dry the material on towels prior to bagging.

If you are harvesting several substrate spawners at the same time be sure to clean the net you use (and other equipment) very carefully. You don't want to have fry popping up in places that are unplanned. To the untrained eye female Cynolebias can all look alike.

Depending on the heat in your room and the dampness remaining in the peat after squeezing, the peat should be ready to bag in an hour or so. Like previously mentioned, we find that just squeezing the coconut renders it the proper dampness so waiting does not seem to necessary. This is the touchy feely part...it's where experience comes into play. After you have done this a few times you will feel a whole bunch more comfortable and know when to bag the stuff. Some have described the dampness as that of fine pipe tobacco...I don't smoke so have no clue as to what that would be. After I squeeze the material, no water comes out and the clump in my hand would not hold together very well. This no water/ clumping thing happens with both peat and coconut. The peat is still dark brown and a few of the tips of the peat may be a lighter shade of tan. Coconut stays dark reddish brown.

We place the spawning material into "zip lock" plastic bags. The bags are labeled with the species and the date. Remember to label them with all of the information...a complete genus/species/location. It's funny how you can forget what the name of the fish is after a couple of months. If anything has been unusual about the collection...a trio rather than a pair...two weeks rather than one, we make a notation on the bag. It is nearly impossible to remember much about any particular bag of eggs several months down the road. You need to think about the bags being stored for at least 2 months...several species take the better part of a year.

We keep our eggs on a shelf near the top of the fishroom. There is a thermometer in the eggs box. The temperature stays about 75 degrees. Cooler temperatures would slow the incubation, hotter speeds the process. Too fast and the fish may be deformed when hatched (we have heard stories). Because we are not in any particular hurry to hatch the eggs we don't mess with temperature manipulations.
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