Koi fish breeding tips.
Stephen M. Meyer
Q. I am a 13-old who, unlike any of my friends, breeds fish. I recently decided to build a pond in my front yard.
This will be my first pond, and I am planning to make it kidney shaped: 12 feet long, 6 feet across, and 2.5 feet deep. Because all I've ever bred are livebearing fishes, I would like to try a bit of a challenge by breeding koi.
I have heard all kinds of things about removing any submerged plants and putting in a scented mat that the female is suppose to deposit her eggs on. I've also heard about hanging a breeding mop in the pond — but I haven't the foggiest idea what that is. I would greatly appreciate any information on the easiest and least expensive way to breed koi.
Also, can I keep the fry in a bare tank on my screen porch, or will it freeze? I plan on getting one or two 1000-watt pond de-icers for the pond, but can a regular 100-watt heater work in a bare 20-gallon tank that is outside? We have winters here with temperatures near 0 degrees Fahrenheit.
A. Koi are very easy to breed. Your initial goal should be to gain some basic experience raising koi fry and culling deformed animals. For this all you need is a mature female and several mature males.
Breeding behavior is stimulated by lengthening daylight and warming water temperatures in the spring. The fish need a cool overwintering location to get into breeding shape. By late April you will almost certainly end up with fertilized eggs.
A breeding mop — or spawning mop/matt — is just a handy device for catching eggs for easy removal from the pond. Koi are egg scatterers, depositing many tens of thousands of eggs at a time. These eggs will stick to any surface they come in contact with. The mop gives you a chance to remove the eggs before the fish eat them (yes, when the koi finish breeding they turn to eating the eggs). The mop also helps cushion the physical impacts the female koi endures during mating.
You can use several simple cloth/rope floor mops as spawning mats. There are also commercial mats for sale, but floor mops work just as well. Koi begin spawning early in the morning. When you hear splashing and see chasing in the pond, hang the mops at a few locations around the pond edge just at and below the surface. The female will head for it.
Allow the eggs to remain in the pond until you see the fish starting to eat them. Them remove the mops to a large container filled with pond water. I would recommend a new trash pail of at least 32 gallons — bigger is better. Depending on the water temperature you should see fry with a week or so.
Your 20 gallon tank will definitely freeze on the porch. Although the 100-watt heater may keep the tank from freezing solid, the fish will not survive. You will have to keep the tank indoors.
Properly raised koi fry can reach lengths of 1 to3 inches by fall, depending on food supplies. Therefore your 20-gallon tank will not hold that many babies. Be sure to cull out all but a half dozen of the very best juveniles.
And lastly, I suggest that when the time comes to buy your pond supplies and pond fish, you find another pet store. If they cannot take you seriously when you ask question then they do not deserve your money. There are many fine aquarium stores and suppliers of pond materials that will take the time to help a serious hobbyist of any age.