There really is no big mystery to surround this stuff. It’s a simple free floating algae. It needs light and nutrients to grow. There are a number of varieties which I don’t care to know all that much about but I can tell you there are salt water types and fresh water types and they all need light and nutrients.

We use greenwater to feed directly to the smallest fish larvae. We also use greenwater to feed several types of other live food cultures, daphnia for example.

Fill a bucket with water. Let it sit for a few weeks. Throw some dried lawn clippings into the water (a handful will do). Add a teaspoon of Miracle Grow plant fertilizer to the bucket and wait until the water turns to soup. The culture will not smell if you have done it this way. If you try to add other ingredients you may introduce additional bacteria and if the bacterial count gets too high that may make the mixture smell and it may smell very bad. While bacteria may be good food for infusoria cultures, they are not necessary for green water production.

The green water is good for feeding cultures of daphnia, moina and rotifers. The green water is also good for small fry, like those of Rainbows, Gudgeons, Bettas and some of the Killifish.

A potential problem with the Miracle Grow method is the phosphate buildup in the water. If you are using the greenwater for feeding other foods and then harvesting the other foods to feed the fish you will probably not experience any problems. If you are using the greenwater to feed directly to baby fish.

Method number two for growing greenwater takes some patience and is not nearly as fast or quite as productive as the method described above. This method works well and is good for those precautious types who don’t want to feed a phosphate laden food to their fish. This is the merhod which we employ at The Bug Farm. This method calls for a big bucket or tub (say 30 gallons of water in a garbage can) and letting the water age for a couple weeks to rid the initial water of chlorine. The next step is taken by adding feeder goldfish to the water (we try for one per five gallons). They will eat the mosquito larvae and algae on the sides of the container and by naturally processing those foods create an environment ripe for green  water to flourish. We feed the goldfish copious amounts of food and by purposely over-feeding help them to produce more fertilizing nitrogen compounds.

Of course if the goldfish have a disease or develop one, your culture should not be used to feed other fish. But because of the harvest and re-filling cycle of our algae production, we find that disease amoungst our goldfish friends to be a very minor (even called rare) occurance.

Feeding greenwater is easy. Remove a small amount and pour the stuff into the fry tank or at least that’s what we do. We don’t like to use so much that we see the tank’s water turn green but we want to know that the young fish have enough to eat. It depends on the richness of the culture as to how much we add. Remember this is a suspended algae you are adding to the water. If there are not enough nutrients in the water to keep the algae alive, it will die and precipitate out of the water column leaving little greenish clumps on the bottom of the container and begin to rot like any other plant. The green clumps can and should be removed with water changes (which, of course, you do on a regular basis).

One of the challenges that one tends to forget about is the light requirements of the micro algae. While these suspended plant-like things tend to grow all year in my neighborhood, they might not in yours. The light requirement stays the same even with the days get shorter and the the air temperature gets colder. One tends to get all geared up and to develop a dependency on the greenwater which by the end of summer can be like thick pea soup and then the days shorten...the sunlight is not available and the greenwater crashes. Another aspect of the need for light comes into the picture when you try to grow the greenwater in a garbage can. Because the can is deep and because the algae grows in the light, the deeper one probes into the water the less algae one will find...whether it is the suspended unicellular variety we seek in "greenwater" or whether it is the type that is attached to the side of the container. We have recently begun using white plastic barrels for our production. They are somewhat translucent and the light has the opportunity to penetrate some of the entire water column. The fish provide the circulation for the water to change position in the container.

A couple of years ago we developed a project that allowed us to grow significant amounts of dense greenwater cultures indoor. By controlling the production and the quality of the algae we had been able to grow about a 1/4 teaspoon of daphnia per 2-liter container per day. The project had also given us the freedom to grow steady supply of greenwater for the smaller baby fishes. However, the price of electricity in our area has forced us to curtail this project...thank you Enron.


This is not a thing but a myriad of critters. There may be any number of critters in the mixture and may include paramecium, rotifers and the like. There will need to be some bacteria available for these critters to feed upon. The bacteria needs some decaying organic matter for food such as old leaves, hay, grass, manure, milk. A word of caution if you get the bacterial count too high, your neighbors blood pressure will skyrocket (let alone a spouse or a family) as the count rises so does the aroma (or perhaps stench). A very healthy bacterial bloom can be had with a relatively small amount of decaying material. Be patient. If the culture is not blooming in the first week, don't add more material. Wait another week and re-evaluate.

In an appropriate container, a gallon glass jar is perfect, put a small handful of crushed lettuce or crushed hay and fill the container with water taken from your aged aquarium. The culture should turn cloudy in a day or a few days and then can be inoculated with some well aged aquarium water (to re-seed the process). It may take several days for the water to clear, but when it does you should be able to see clouds of infusorians hopping/glided/jefking/swimming through the water.

Using a magnifying glass, and a flashlight to backlight the culture should help you see the infusorians.


While these may not be the perfect food they are available year round and can be cultured in your fish room with little smell and cultured in a very small area.

Take a quart jar and fill it with distilled water. If you use aquarium water you may be introducing other organisms (see above) which may feed on the paramecium you are trying to culture. If distilled water is a problem for you, boil some tap water to kill bacteria. Boil about 15-20 kernels of raw wheat. Boiling softens the kernels and begins to break down the outer shell so that it can decay. Wheat can be found in health food stores and some grocery stores commonly called Wheat Berries. Add the boiled kernels of wheat and about a ¼ teaspoon of Brewers Yeast to the distilled water stir until dissolved. The mixture will be cloudy. Add your paramecium starter and set the jar aside (covered with a couple of small holes punch through the cover) at room temperature light is a good thing. The culture should be ready to use in 2-3 weeks. Start a new culture every 2-3 weeks to assure yourself of a good and ongoing supply. The culture will be good for about 2-3 weeks after it gets going. Temperature has a lot to do with the 2 or 3 week time recommendations. We have 2 sets of jars going all the time.

"We grow food not bait"