Any sort of non toxic plant matter can be used to make an infusoria culture. I recommend lettuce because they are cheap and readily available in most parts of the world. But spinach, silverbeet, cabbage, broccoli, oak leaves, or any leaves from non toxic plants, and even grass clippings can be used.
You need to add a lot of plant matter to the water, 1 whole lettuce per 20 litres (5 gallons of water) or an equivalent amount of plant matter. You would need about 5-6 large spinach plants to equal 1 whole lettuce. If you get a 10 litre (2.5 gallon) bucket and loosely fill that about 2/3s with leaves or lawn clippings, that would be about the same as a lettuce.
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You normally use tap water for the culture so you get a pure culture of infusoria. Any water can be used including seawater (if you're rearing marine fish fry). But clean water is generally used to make clean pure cultures that don't have other things in them. In an aquarium you can have hydra, snails, planaria and other sorts of small or microscopic organisms and most of them love the same types of bacteria that the infusoria (paramecium) eat. Hydra and a lot of other small creatures (including aquatic insect larvae) will also eat the infusoria. Using tap water will stop these other unwanted organisms getting into the culture and eating the infusoria or building up in numbers and eating the fish fry.
You need to have the cultures covered to stop mosquitoes laying eggs in it. Mozzie larvae love to eat infusoria and will also eat fish fry. Other insects will also take up residence in the culture if they can get into it.
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You do not need light for an infusoria culture to grow. The bacteria & infusoria don't care if it's light or dark and normal room light is adequate.
It takes 2 weeks or more before the culture starts to clear and before the infusoria start to grow. Think of this as a bit like cycling an aquarium. It takes a few weeks for the first lot of filter bacteria to grow and after it has grown, the ammonia levels come down and the nitrite goes up. With infusoria cultures the first couple of weeks are where the bacteria grow and feed on the rotting leaves, then the infusoria starts to appear and build up in numbers after the bacteria have established.
Once the culture has started to produce infusoria and you have started to harvest them, you add a couple of crushed up lettuce leaves (or some other type of plant matter) each day to provide food for the bacteria, that in turn provide food for the infusoria. If you don't add new leaves each day or every couple of days, the bacteria eventually stop growing and the paramecium run out of food and you run out of paramecium to feed to the fry.
The new leaves only have to be added after the culture is established and you do not have to add leaves while it is developing. The new leaves are simply to extend the cultures life and keep it going for a few weeks, which is usually long enough for the fry to be moved onto newly hatched brineshrimp.
If you have 2 or more cultures going you can harvest from one in the morning, one at lunch and one at night. This gives the cultures more time to recover between harvests and gives you a back up culture if one crashes, which can happen in really hot weather or it you forget to put the airstone back in. Cultures also die after a period of time so if you plan on breeding fish you should start new cultures every few weeks to ensure you have a plentiful supply of fry food when you get fry.
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You can use almond leaves and the water will turn brown. Once the culture is growing well, you can use a torch to see the infusoria, they almost glow white in dark tannin stained water. We had a pond that ended up with a pile of Eucalyptus leaves in the bottom, there was about 1 foot of leaves in the bottom of this pond. The water went really dark (almost black coffee coloured) due to the tannins. One day we noticed white clouds in the water and the pond was completely full of infusoria. It had a dead lizard in it too and about 6 billion mozzie larvae. Needless to say, the fish were fed well that day and for a few weeks after that. We were scooping out nets full of mozzie larvae and putting handfuls into each tank with the fish. The infusoria were used for the baby fish that appeared a week after we fed the mozzie larvae to the fish.
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The baby gouramis will be eating the smaller bits of egg yolk so keep feeding that until you get brineshrimp eggs and microworms. You can buy dry brineshrimp eggs online or at pet shops. The eggs should be kept dry and cool. I kept a tin of them in the freezer and filled a couple of small phials with dry eggs that were then put in the fridge. The tin of eggs went back in the freezer while I used the eggs in the fridge during the next week.
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Microworms can be cultured in instant porridge. Get a small plastic container and spread a thin layer of oatmeal across the bottom. Add enough tap water to just cover the oatmeal and then put it in the microwave for a couple of minutes. After a minute in the microwave you remove the container and stir it up before putting it back in the microwave for another minute or so. Remove the oatmeal and mix it again before spreading it out in several small plastic containers (1-2 litre icecream containers work well for this). You have a 5mm (1/4 inch) layer of oatmeal on the bottom of each container and let it cool, this only takes a few minutes. Then you add a teaspoon of microworms (from a starter culture bought online or at pet shops) to each container of oatmeal and put the lid on it. Allow the culture to grow for a week and the worms will spread over the oatmeal and grow up the sides of the container. Use your finger to carefully wipe some of the worms off the side of the container and wiggle your finger about in the fry rearing tank. The worms are tiny and wash off in the water and the fry eat them.
You can add more than a teaspoon of worms to each culture if you have access to a lot of worms but a teaspoon is the minimum you want to add. Drip the worms over the porridge/ oatmeal so they cover more of it faster.
You can feed dry bakers yeast to the worms to help give them a boost. Normally yeast is added one time, a few days after a culture has been started. You can add yeast every few days but the yeast can cause cultures to crash so I normally only add it one time or if a culture is doing well, I might add it once a week while the culture is doing well.
Have several cultures going and start new cultures each week. Keep cultures cool but not too cold, and avoid really hot weather. Normal room temperatures are ideal.
If a culture does not have many worms, you sometimes get fungus growing over the oatmeal. You can take worms from this culture and use them to start a new culture before throwing the furry culture away. Wash the culture containers out in hot soapy water (dishwasher) between uses. Open the cultures up each day for a minute to let fresh air get into them. You do not need to have holes in the lid of the culture and insects will sometimes get into the cultures if you do have holes in the lid.
When cultures start to go off, the oatmeal worm mixtures starts to turn brown and then black and it smells unpleasant. Start new cultures before this happens and dispose of cultures that have gone black or dark brown.
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Algae cultures can be grown indoors and regularly are in scientific labs or aquaculture facilities. You have a couple of fluorescent lights above or next to some containers of water. You either add an algae starter disc (available from aquaculture supply stores (like Florida Fish Farms) or you just leave the containers of water open to the air. Algae spores will eventually land in the water and start the cultures.
If you need to get green water quickly, you can use a clean fish sponge and wipe some green algae off the inside of an aquarium and rinse the sponge out in the culture container. Within a week the water should start to go green and soupy.
The water should have fertiliser added to it. The directions are in the link Back to Basics when Breeding Fish, and you use 1 level tablespoon of lawn fertiliser for every 20 litres (5 gallons) of water.
http://www.fishforums.net/threads/back-to-basics-when-breeding-fish.448304/
Have the light on for 24 hours a day and aerate the water and fertiliser. Use an airline without an airstone to circulate the water. Tie a small lead weight to the airline to hold it on the bottom of the container of water.
When the water goes green and soupy you start to add a liquid aquarium plant fertiliser or an iron based aquarium fertiliser to keep the culture going.
You should start a new culture regularly by making up some clean tap water and fertiliser and adding some of the green water you already have.
You can use old green water cultures to grow rotifers, daphnia & cyclops.
