Slipper Infusoria (Paramaecium caudatum).
Infusoria (Infusoria) are single-celled animals belonging to the type of protozoa, single-celled microscopically small creatures, of which there are about 8 thousand species. Among the many species of ciliates, the main place is occupied by Paramaecium caudatum, the size of which is from 0.1 to 0.3 mm. Of all protozoa, ciliates have the most complex structure. It got its name due to the shape of its body. In shape, the body of the slipper really resembles the sole of a shoe. The outer layer of its cytoplasm is dense, due to which the constant body shape of the ciliate is maintained.
The entire body of the ciliate is covered with longitudinal rows of small cilia, with the help of which Paramaecium caudatum moves, making wave-like movements with them. Ciliates move very easily and quickly. Its movement speed is such that in 1 second it covers a distance 10-15 times exceeding the length of its body. To the naked eye, ciliates seem to be moving dots, but with magnification by a good magnifying glass, you can see that these are living creatures.
The habitat of Paramaecium caudatum is any freshwater body with stagnant water and the presence of rotting organic substances in the water. It can even be found in an aquarium by taking water samples with silt and examining them under a microscope. Ciliates feed mainly on bacteria and microalgae, digesting and passing them through themselves with the help of a digestive vacuole formed in the cytoplasm. Small food particles penetrate into the body of the ciliate through the oral cavity (which is always open) and accumulate there. After that, the food makes a complex journey in the body of the ciliate, along which the digestive process is carried out. It multiplies by cell division and conjugation (exchange of genetic material during fusion).
For very small fry, hobbyists keep ciliates “close at hand”. Paramaecium caudatum is a very popular (starter) food for fry of most aquarium fish species. And for some (Gourami) it is irreplaceable. Newborn fry see them well and eat them in large quantities. For tiny fry, ciliates are simply indispensable: most of the fry will simply die. According to analyses, Paramaecium caudatum contains 6.8% dry matter, of which 58.1% is protein, 31.7% is fat, and 3.4% is ash.
You can get ciliates in any stagnant body of water. Ciliates are easily bred at home on various nutrient media. The difficulties of breeding consist in obtaining a pure culture and in purifying ciliates from harmful bacteria. For breeding Paramaecium, it is desirable to have a pure culture. Getting it by separating the slipper from the mass of other ciliates is very simple. A large drop of water with ciliates visible through a magnifying glass is placed on a clean glass. Next to it, but necessarily on the light side, a drop of fresh, pre-settled water without signs of life in it is placed.
A thin water track is laid between the drops with a sewing needle. The slipper will immediately rush along it to the light source, ahead of other ciliates. As soon as the migration of the slipper, at least partially, ends, the access of other ciliates to the clean drop is immediately stopped by disconnecting the water “highway”. After several sorts, you can get material sufficient for breeding the slipper, the culture of which is laid three to four weeks before the expected appearance of the fry.
Necessary conditions for success are: large glass dishes (at least 5 liters), heat of at least 18-22°C, relatively soft water and twilight. They can be kept in any glassware at room temperature. The slippers multiply by division, and the division occurs at least once a day. Under favorable conditions, in a week ciliates can be seen as a mass of whitish moving dots. After a few days, ciliates can already be seen near the surface of the water, where they concentrate, catching bacteria and various particles from the air.
Control over the development of the culture is carried out using a magnifying glass or microscope and, indirectly, by eatability. If it is not eaten by the fry, it means it is not a paramecium or its density is too low. For uninterrupted food production, the setting of the paramecium culture should be staggered in time (in different vessels). It is recommended to prepare several jars with a nutrient medium so that if the nutrient medium does not work out in one, use another.
For continuous breeding, you will need a supply of dried banana peels. As a nutrient medium for paramecia, you can use hay infusion (1-2 g of hay per 10 l), dried banana, pumpkin, melon, yellow turnip peels, sliced carrots, milk, potato peelings, peas, beans, hydrolytic yeast (1g/100 l), etc. It is important not to overdose the nutrition. When sediment, turbidity and an unpleasant odor appear, the culture is recharged.
Vegetable and milk culture. Two containers are needed. In one it develops, in the other there is water to replenish its consumption in the jar with the culture. To obtain a culture of the slipper, tap water settled in the dark (for 2-3 days) is taken and the previously collected planting material is placed in it. You can transfer the slipper from one dish to another provided the temperatures are equal. If you want to get a normal culture of ciliates, it is enough to take one jar and fill it with water from a long-established aquarium. In such water, there is always the necessary amount of ciliates for breeding. However, to make them more numerous, it is recommended to take rotting or already rotting plant leaves from the aquarium and place them in the jar.
In the future, the breeding of ciliates, both pure culture and ordinary mixed culture, is carried out in the same way: a small amount of powdered dry lettuce leaves (but best of all banana crusts) is added to the jar of ciliates. Initially, the portions of powder are the most insignificant. On the 3-4th day in the jar, necessarily covered with glass, the powder will begin to decompose, creating a favorable environment for the development of bacteria – the food of ciliates. In this case, the property of lettuce and banana peel to slowly decompose in dim light and at a moderate temperature is used. This restrains the rapid development of bacteria and at the same time gives the ciliates (so far few in number) the opportunity to gradually cope with their age-old enemies and devour them.
As a result, the ability to breed ciliates boils down to the correct regulation of the amount of rotting organic matter relative to the already existing amount of ciliates. The more ciliates, the more putrefactive bacteria are required for their nutrition and, consequently, larger portions of this or that powder. Under no circumstances should powder be added to cloudy water. This would strengthen the already significant colony of bacteria waging an irreconcilable struggle for life with the ciliates we need. The strongest will win. A sign of the complete death of ciliates is a strong turbidity of the water.
With patient and correct nursing of the culture, 5-6 days after its establishment, the number of ciliates will begin to increase day by day. And then they can be transferred to milk feeding. Decomposing rapidly, low-fat milk contributes to the rapid formation of large masses of bacteria, which is no longer scary, since countless hordes of ciliates are able to cope with them. The ciliate culture is gradually transferred to milk feeding, pouring from one to ten drops of milk per 1 liter of water daily. The amount of milk, of course, depends on the mass of ciliates and the state of their habitat. The more transparent the water in the incubator jar, the more drops you can pour into it. Fish fry are fed with ciliates so as to introduce as few putrefactive bacteria as possible into the spawning ground. Their excessive amount can ruin the water and destroy all the young fry.
If the culture medium is too cloudy, then, having stopped feeding bacteria for a few days, you should wait for the water to clarify. When feeding fry, two or three culture jars are usually operated alternately. It is easiest to select ciliates with a special pipette-like device, immersing the tip instead of their largest accumulation. The device consists of a rubber bulb and a glass tip tube. The daily consumption of water with ciliates is replenished with the same amount of water from a spare jar and, most importantly, at the same temperature. Further feeding of the culture is carried out in the usual way.
Hay culture of ciliates has its own feature: the established culture must not be disturbed by feeding or adding water. Having started feeding the fry with the formed culture, feed it to the end. The establishment of such a culture begins with the preparation of a nutrient medium for the habitat of ciliates. An enameled saucepan filled halfway with hay cuttings (meadow hay is better) is filled to the top with water and boiled for an hour; the cooled broth is filtered and poured into a glass dish (at least five-liter), and the missing part of the water is taken from the aquarium.
“Old” water, in which decay processes hardly occur, is unsuitable for establishing a culture. Water should be taken from aquariums with regular partial water changes. From the same aquariums, it is useful, as in the first method of establishing a culture, to collect rotting leaves and stems of plants, squeezing large quantities of ciliates from them into the nutrient medium. The mixture of broth and aquarium water should have the color of strong tea.
The development of the culture requires minimal light and a temperature not exceeding 18-20°. Strong light and heat accelerate decay processes, and in the incubator jar they should occur at a slow pace. Almost the day after the culture is established, the water in the jar will become very cloudy and emit a sharp putrid odor, which, however, should be ignored. Gradually the odor disappears, and after 5-6 days in the upper layers of the water, most rich in oxygen, large accumulations of ciliates will appear.
Destroying bacteria, ciliates will begin to sink lower and lower and in 2-3 weeks, when almost all bacteria are destroyed, they will occupy the entire water space of the jar, and the water will become almost transparent. This time is considered most suitable for feeding the culture. For uninterrupted supply of ciliates to the hatched fry, it is recommended to establish two or three jars of hay culture at intervals of 10-12 days. From pouring water with ciliates, the spawning water acquires a yellowish color, but the fry do not suffer at all.
To feed the fry, ciliates must be introduced into the aquarium with as little water as possible in which they reproduce. Therefore, the final stage is the separation of a portion of microfood, using the ability of ciliates to move towards light and fresh water. To do this, water with ciliates is poured into a bottle with a high neck. A piece of cotton tied with a thread is pushed into the neck so that it touches the water, and a layer of fresh settled water is carefully poured onto the cotton. It is better to expose the bottle to bright light and wrap it with black paper from the bottom to the level of the cotton. An hour later, ciliates will gather in fresh water, which are sucked out with a pipette.
Ciliates are harvested by suction using a rubber hose or bulb in places of highest concentration, using the effect of positive phototaxis (movement from darkness to a lighted place) or medium separation. Before harvesting, fresh water is added to the neck, fenced off with a capron or cotton filter. After 30 minutes, the ciliates move to a clean area, from where they are sucked out with a hose. And this water is passed through filter paper or dense fabric. Together with the paper or fabric, they are placed in the aquarium where the fry are fed. It is advisable to put the filter paper on the surface of the water on the side where the ciliates remained. A floating branch of hornwort or a foam plastic frame will help keep the paper on the surface.
Feed the fry with ciliates 3-4 times a day, in accordance with the strength of the brood. To concentrate ciliates in one place, which makes it easier to find food, you can from time to time place small pieces of banana peel or carrot pieces in the spawning ground. Being at the very surface of the water in a capron mesh and slowly decomposing, they will begin to attract bacteria, providing them with food, and bacteria – ciliates hunting for them. At this time, periodic aeration of the water with a weak spray of air is useful.
Vinegar eels or nematodes, microfeed. Turbatrix, Panagrellus.
Feeding with planktonic rotifer species. Brachionus, Asplanchna, Philodina. 
