Author Topic: How to Breed Plant-spawning Killifish  (Read 3650 times)


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How to Breed Plant-spawning Killifish
« on: August 13, 2012, 09:57:31 PM »
The following is from the American Killifish Association's "Beginner's Guide" which you can find at

Plant Spawners

The plant spawners lay their eggs on floating or submerged plant thickets. They include many genera, such as Aphyosemion (most), many Fundulopanchax, Aphanius, Aplocheilus, Epiplatys, Pachypanchax, Fundulus (most) and Rivulus (except for Rivulus stellifer). In the aquarium there are several techniques that can be used to spawn these fish.

1.  The Mop Method
The most popular method of breeding plant spawners is the use of mops constructed from nylon or 100% acrylic yarn. The fish deposit their eggs on the strands of yarn. Organic yarns, such as wool or cotton, should not be used as they deteriorate in the water. The color of the mop does not seem to be very important, although some killie breeders claim that their fish prefer certain colors. Dark colors, particularly dark green, are often used. In all cases it is necessary to boil the mop before use.

Construction of mops is not difficult. A cork, approximately 1.5 " diameter and 3/4 - 1 inch thick, is used for floating mops. A narrow groove is cut around the entire circumference of the cork. Next, the yarn is wrapped 30-50 times around a rigid piece of cardboard, or a book, of suitable size. The width of the wrapping should approximately equal the circumference of the cork. Several strands of yarn are then cut and threaded beneath the wrapped strands at one end. The whole thing is then slipped off and tied to the cork, adjusting the distribution of the strands uniformly around its circumference. Finally the strands are cut opposite the cork such that each strand hangs individually. This type of mop is generally better, and easier to search, than mops made by tying a bunch of strands into a knot at one end.

For bottom spawning killies, mops are made by simply tying at one end, without the cork. When thoroughly wet, these mops sink to the bottom of the breeding tank.

For breeding the mop is placed in a tank housing the breeders. The breeding tank is usually devoid of substrate, as many killies would choose to lay their eggs in the substrate. As many species of killifish will lay their eggs in either a floating or a bottom mop, one or each, or a long mop whose strands reach and lay on the bottom of the aquarium, may be used. 

1a.  The Water Incubation Method
Every two or three days the mops should be removed from the aquarium and the eggs harvested. Excess water is removed by gently squeezing the mop and then rolling it in an absorbent towel. After several minutes, the mop is ready to pick. Examination should be under a strong light. A plastic container containing clean water from the breeding tank can be used to incubate the eggs. A fungus preventative, such as acriflavine can be used. Often the eggs will develop and remain healthy without the use of a bactericide, but a little caution may pay off. The eggs can be removed from the mop with tweezers or fingers. It is best to remove eggs by placing fingers or tweezers behind the eggs, rather than by grasping it directly, and lifting outward from the mop. Newly laid eggs may be too soft for harvesting, as it takes a few hours after being laid for the eggs to harden. If this is the case, the mop should be returned to the breeding tank for a few more hours. Eggs that are cloudy in appearance and eggs that collapse when touched, should be discarded as they are presumably infertile and will be attacked by bacteria. Clear eggs are placed in the incubation dish. They should be examined daily and any which have fungused should be removed. Fertile eggs will gradually darken until the shape of the soon-to-hatch embryo is clearly detectable, the most prominent feature being the eyes. In fact, you will often hear killie breeders talk of "eyed-up" eggs, meaning that the iris of the embryo is clearly visible and that the eggs are ready to hatch. Eggs of most plant spawners will hatch from 10 - 21 days after harvesting.

As the eggs hatch the fry are removed (a large dropper or baster works well for this job) and placed into small growth tanks. The water should be the same chemically in the rearing container as in the incubation chamber, and the temperatures equal. Aeration or filtration is recommended, but not essential. First food is normally newly hatched brine shrimp or microworms. Many aquarists add a small amount of salt to the rearing tanks, which cuts down the growth of bacteria and keeps the baby brine shrimp alive longer. Caution is necessary to avoid putting in too much salt as it could kill the fry. As the fry are likely to hatch at different times, several growth tanks should be provided to insure that the fry in the same container are of similar size. Larger fish are likely to look upon the smaller ones as food!

On occasion eggs that appear to be fully embryonated (eyed-up) will not hatch. If left in this condition, the embryo will eventually die and the egg turn a gray color. Under these conditions it is advisable that the eggs be forced to hatch. This is accomplished by placing the eggs in a container (a small vial) with a small amount of water (about 1/4 full). In some cases simply walking around with the vial in one's pocket will cause the eggs to hatch, presumably due to the agitation. One can also blow into the container and quickly cap it. This increases the concentration of carbon dioxide and causes the eggs to hatch. An alternative is to place some fast decomposing food in the water, but the fry must be rescued quickly or they become the victims of the pollution. One other method is to place a small quantity of microworms in the hatching container. This will often force the eggs to hatch, either due to movement or to increased CO2 concentration.

1b.  The Vaporizing Method
Another problem that frequently occurs is that the eggs seem to go bad no matter what is done, even though the eggs are initially fertile. When this happens many hobbyists have achieved success by using an alternative to the water incubation method, namely the vaporizing method of eggs storage. Eggs are placed upon wet peat moss (some use a sponge). The peat moss is placed (after boiling and cooling) in a container with a tight fitting lid and the eggs are taken off the mop and placed on the surface of the peat moss. The peat should be quite damp and it may be necessary to add water to it from time to time. Bad (white) eggs should be removed daily. This method takes somewhat longer for the eggs to develop than does the water incubation method, but it sometimes works when the standard method fails. Eggs that go bad have less chance of infecting the good ones as the bacteria are less able to move about. One other advantage of this method is that the eggs can be hatched en mass thus allowing a batch of fry of similar size to be raised.

2.  The Permanent Set-Up Method
Another successful way of propagating the plant spawners is to use a method similar to the one employed by nature; let the fish spawn in the tank and, when the fry appear, take them out for raising. Many species of Aphyosemion and such species as Epiplatys annulatus have been bred in this manner. Another alternative is to move the parents to a new breeding tank after a suitable period, allowing the fry to hatch and grow in the original tank.

When using a permanent set-up, it is best to use a fairly large aquarium (10 gallons or more). The aquarium should be densely planted from top to bottom. A thick plant covering at the top is especially important for the fry. This method does not always produce large numbers of fry but the ones that do survive are usually very robust. There is the added advantage of having a beautiful display tank and of not having to pick eggs. Many of our European friends use this method exclusively, insisting that the resulting fry are of far greater quality than are those raised using other methods.

3.  The Peat Moss Method
For several years the use of peat moss as a spawning medium was thought to be useful only for soil spawners. Many aquarists, however, have found that many non-annual species of killifish will readily spawn into a substrate of peat moss. It is simply a matter of collecting the peat moss and placing it into a plastic bag (first allowing it to drain of excess water) and waiting from three to four weeks, after which the peat moss is placed in aged aquarium water. The fry will then hatch, frequently in large numbers.
« Last Edit: August 27, 2012, 09:49:01 PM by azkillie »