It is said that before one goes to war, one must make sure the logistic is secure. It is the same when one wants to breed goldfish, one need to secure the supply of food for the fries. The continual availability of the food is very important to the fries. Later development of the fish depends heavily on the development in this early stage. The two best choices food for the fries are daphnia and artemia.
Different place might prefer different choice. In the place where I live (Indonesia), artemia is expensive and the preparation process is tedious. Daphnia – or is known as “kutu air (water flea)” here – is the best choice. If one can find a place near one’s farm that yields plenty of daphnia daily, it is the ideal scenario. I once had this kind of place. It was a river with shallow banks 10 minutes of motorcycle ride from my house. I scooped enough daphnia for my breeding activity everyday for free. It was a time of prosperity.
However, the supply did not continue for long. As flood came in the wet season, the daphnia was gone. I must wait till the next dry season to come when the daphnia became plentiful again. However, as the daphnia hunter became more numerous, the supply began to diminish. People harvested the daphnia without consideration, and soon the daphnia were gone forever from that place. I had to depend on buying from a seller to supply my daphnia need. However, buying daphnia everyday can be very expensive. I begin to look for a way to cultivate the daphnia myself.
I consulted many books and articles in the internet, and experimented a lot for years, constantly finding a better, cheaper and easier way to culture daphnia. It is not easy to culture it. At least, it is not as easy as the book said and the articles wrote. However, the books and articles help a lot in understanding the way it reproduce and what it consumes. I will just give a very short summary on this since many have written about this in length. At the end of the day, one will need to experiment alone to find the most suitable way for oneself to culture daphnia. What is easy and what works for me might not be so for others.
Concerning daphnia’s reproduction, I will say that this is an amazing creature. When the environment is conducive, it will reproduce by cloning itself. So there is no need to mate with opposite sex. We can start our culture using just one single daphnia! When the environment gets harsh, if there is time, the daphnia will produce male offspring. The male and the female will then mate to produce eggs. The eggs will survive the harsh environment for a long period of time, and when the environment is conducive once more, the eggs will hatch and will start cloning itself again. So, this is a creature that can reproduce in two different ways. It is so amazing. So, the first task is to maintain an environment which will be conducive for the daphnia to clone itself. We do not want the daphnia to lay eggs, or worst – to perish.
Concerning the food, basically it eats all organic particles in the water, including bacteria. So the second task is to find the best available food that will boost the production of daphnia.
There are many types of dahpnia. The one needed for goldfish breeding is the more common and small one, such as the Daphnia Pulex. The freshly hatching goldfish fries will eat the babies of the daphnia, which is usually hard to see with bare eyes. People often think that the freshly hatching fries can eat adult daphnia already, which is not the case. It will need a few more days before the fries can eat adult daphnia. Another famous type of daphnia is the giant daphnia (Daphnia Magna). Due to its size, it is not useful for fries less than 3cm in length, which is roughly equivalent to one-month-old fries.
The more useful one, which is the small daphnia, is harder to cultivate compared to the giant one. Yet, this small daphnia is the subject of this article. The difficulty can be described in this way: when lack of food, the daphnia will perish, but when the food is over, the water will become foul and the culture will crash. So, it is hard to determine the balance. This is not the case for daphnia magna. When lacking of food, the daphnia magna can still survive.
The method I use to maintain the water quality for the daphnia culture is to have a routine partial water change, and to have two cultures of daphnia. The routine partial water change is to prolong the time before the culture crashes. The culture crash must be accepted as a fact, and it will sooner or later happen. So, the partial water change will help the culture not to crash too soon. When the production of daphnia reaches its peak, that is, when we can harvest plenty of it satisfactorily, it is time to start the second culture. When the first culture’s yield is decreasing, and the water is getting bad, then it is time to start it all over again. By this time, hopefully the second culture has reached its peak. The partial water change is done only when the culture is in its peak. There is no use to change the water when the culture has not reached its peak or close to it. The partial water change must be done routinely. How routine is it? It will depend on the situation. If the feeding is very intensive, using food that can easily foul the water, then the water change might need to be done daily, or even twice a day. But if the water does not easily become foul, then the schedule can be lessen into once every three days or so. This is the method I use to maintain the peak performance of daphnia’s yield.
Concerning the food, I have experimented with many things such as milk powder, fish pellet powder, vegetables, green water, rice soaking water, etc. People say activated yeast is good, but I have not tried it. I have never tried animal’s excrement, either, for it is unthinkable to use in a city house. Lately, the most satisfactory ingredient I use is the organic household garbage. It is easy, and cheap, and it yields almost instant and abundant result. I ask my maid to gather the leftover from the kitchen, such as chicken and meat leftover, bones, vegetable and fruits leftover, egg shells, rice leftover, unused seasoning, tofu, etc. This is a superb food for daphnia as long as it is free from chemicals such as pesticide. The drawback is when the garbage is too plenty, there is a bad odor, which is not desirable. But when the garbage is not over, and is fully soaked in the water, then the smell is tolerable. So, it is good to plan ahead where the culture will be held. An open area where there is plenty of fresh air which is not close to household activity is better. I encourage you to try how much garbage is needed to start your own culture. Start from just tiny amount of garbage, because even a bit too much for the start will foul the water and crash the culture quickly. You can increase the amount later if you think it is not enough.
Since I have many breeding activity, my need of daphnia is a lot. So I culture my daphnia currently in two ponds 3m x 1m each. Each pond only needs a plastic bag full of garbage for several days. So the garbage needed is just tiny compared to the pond size. I have not done this in aquarium or small tub setting, but I think this can be done easily using the same method. Hope this help. Good luck.