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Most aquatic zooplankton are natural food for fish, and generally refer to what we often call rotifers, water fleas ("tassels" with fleas, non-"algae", the same below) and other micro-aquatic organisms such as copepods. Rotifers are invisible to the naked eye, water fleas are visible to the naked eye, and they are all high-quality natural food for fish. Aquatic zooplankton are commonly present in freshwater water bodies, as long as there is a certain degree of fertility in the water, there are widespread sources of rotifers and water fleas, therefore, the general water spray seedlings do not have to deliberately cultivate "insect fleas", the pond water naturally exists, just the appropriate pond clearing, water and fertilization and other series of operations can be expanded.
(Aquatic zooplankton)
In real production, everyone knows that rotifers are the most suitable natural opening bait for splash seedlings. However, some people mistake water fleas for wheelworms, not knowing that the two are similar in size, use, or growth time, but more effective and palatable. Rotifers are the most suitable for the opening bait (note the "opening") in the early stage of the pond under the water splash fry), and the water fleas are the suitable bait for the late stage of the water splash seedlings, but in the adult stage, if the zooplankton, including water fleas, breed too much, it will cause an oxygen-starved pond accident.
(Splash seedlings)
Rotifers are the opening bait for splash seedlings
In the case of splash seedlings, due to the small caliber of the water splash seedlings, the water spray seedlings that only go down to the pond can only swallow rotifers, so the best opening bait is the rotifers (not water fleas). Generally, the seedlings will eat larger water fleas after ten days after the water spray seedlings are in the pond (about 1 cm of wuzai seedling size), so the water fleas can only be the natural food for the small fry (not the water splash fry).
In aquatic production, the so-called "fat water pond" is the core of which is to prepare for the suitable bait under the pond of the splash fish fry. Fertilization and cultivation should be mastered in good timing, too early or too late, the biomass of rotifers has not reached the peak or the peak has passed, these are the appropriate time to grasp the timing of fertilization and water cultivation. After fertilization in the pond, the law of the formation of peaks by various types of zooplankton is: the first peak is the protozoa, followed by rotifers, then the branches, and finally the copepods. This is the same as the requirements for food size change in the whole growth process from the pond to the summer flower (inch seedling) of the water flower fry: protozoa and rotifers → small branches→ large branch → copepods, which is consistent with the order in which the pond zooplankton form peaks. Pond timely fertilization and water can make good use of the consistency of the two, so that the splash fry just appear after the peak of the rotifer after the pond, not only the splash fry that has just entered the pond has sufficient palatable bait, but also can have a wealth of palatable bait at all stages of development in the future. Therefore, timely fertilization and timely release of splash fry into the pond are the keys to raising fry.
Rotifers
The rotifers in aquatic plankton are excellent open bait for many aquatic fish (such as loach, etc.) in the nursery stage of the pond under the splash, it is also the smallest micro-animal available in zooplankton, it is not as visible to the human eye as water fleas, people can only look at the sun by holding water in a glass, when there are small white dots in the glass water, it can be regarded as a rotifer, and it can be clearly seen with a microscope. Rotifers are small and diverse, cylindrical, oblong, pouch-shaped and spherical, etc., surrounded by transparent cornea, and the front of the body is a roulette wheel with clumbled cilia, so it is called rotifer (which is similar to the wheelworm).
In the general fish pond bottom mud, there are deposits of a large number of rotifer eggs, in the pond bottom of the pond with many years of fish farming and silt thick, the surface layer of 3-5 cm of silt, according to some tests, the amount of rotifer winter eggs per square meter can reach hundreds of thousands or even millions, up to more than 10 million, they are the "seeds" of pond rotifers. As long as the environmental conditions such as water temperature, dissolved oxygen, and fertility are met, the eggs can germinate and grow. Rotifers reproduce as parthenogenetically when food is sufficient, temperature and other environmental conditions are suitable, and the mother after sexual maturity lays several eggs at a time, and the eggs that can be hatched without fertilization can hatch in 10 hours at a water temperature of about 25 ° C, and grow into adults after a few hours, and then reproduce; when environmental conditions deteriorate (insufficient food, insufficient dissolved oxygen, temperature discomfort, etc.), the mother lays small or large eggs, and the small eggs hatch males and large eggs hatch females (hybridization), After mating, the female produces a fertilized egg (winter egg) coated with a thick egg shell. Most of these winter eggs are deposited on the bottom of the water, and can tolerate long-term low temperatures, droughts, and a considerable degree of resistance to drugs.
(Folded arm-tailed rotifer)
In the early spring after the fish pond clears the pond, generally in about 6 days in the pond is likely to reach the peak, therefore, at low temperature in the splash seedlings about a week before the pond to add water is appropriate; in the summer and autumn period of the water temperature of about 25 ° C, as long as 1 to 2 days, the rotifer biomass can reach the peak, therefore, in the summer and autumn period, in the summer and autumn period, in the splash seedlings about 3 days before the pond to add water. If you add water to breed "insects" in advance, it may be that when the waterfolium seedlings go down to the pond, the rotifer period has passed, and a large number of water fleas appear in the water, which is seriously detrimental to the waterfoam seedlings (many people are most likely to mistake the water fleas for rotifers at this time, and they are very happy).
Generally after the pond is cleared, at the right time, the peak period of rotifers can be maintained for 3-5 days, at which time small branches (such as bare-bellied mud) begin to appear. Generally appears after the peak period of 3-5 days, the branch horns appear peak, rotifers appear winter eggs, that is, the reproduction of rotifers has stopped, at this time generally need to use rotifers to re-breed by fertilizing and injecting water.
In addition to the above-mentioned natural breeding method of fertilization and water cultivation, there are also professional breeding rotifer methods, which can use yeast and photosynthetic bacteria as bait, fish plankton from the pond to separate rotifers under the anatomical microscope, in the culture process, to maintain enough light, photosynthetic bacteria and other strains have a significant role in promoting the growth of rotifers (don't think that the fungal algae we usually put into the water, sometimes also become the bait of rotifers, water fleas and filter-eating fish), there are also special rotifer eggs for sale on the market. Breeding rotifers can be harvested when the density of breeding rotifers exceeds 100 / ml, can be made of 250 ~ 300 mesh mesh mesh mesh mesh cage, cage height 40 cm, the outside with stainless steel frame support, cage bundled tightly inside the stainless steel frame, the cage together with the stainless steel frame placed in a large plastic basin with a height of 20 cm, with a water pump (or water wheel type aerator) to extract the pool water, through the plastic hose into the cage filter, you can harvest rotifers.
(Collect zooplankton using a waterwheel aerators)
In the early stage of the water bloom nursery pond (about 10 days), when the eclamps do not need to be arboplankton, the occurrence of phyllodonts can be controlled by enemy insects at this time, and the appropriate amount has little impact on rotifers. Small branches such as the stinging naked-bellied insect can be killed with 0.05-0.5 g/m3 of crystalline diphtheria, and 0.5 g/m3 for 0.5 μm of fuzzy bare-bellied and copepods, a concentration of which is toxic to the spiny tail rotifer. Therefore, the commonly used amount in production is 0.2-0.5 g/m3. The peak period of rotifers can be extended from 3-5 days to 7-10 days, and repeated medication may continue.
(Hydra under the microscope)
water flea
Water fleas, belonging to the branch horns of zooplankton, some people call "water spiders", also known as "fish worms", red worms, body length is about 1 mm, often clustered together to do smooth, slow and other jumping movements. Water fleas colonize the surface layer of the water when the water temperature rises, and inhabit the bottom layer when the water temperature decreases. In the early stage of splash seedlings, the water spray seedlings can not eat it, and the water fleas instead grab the material (such as phytoplankton, cooked egg yolks, raw soy milk) and consume oxygen. Water fleas feed on phytoplankton, reduce the oxygen-making function of phytoplankton, will make the water body hypoxia, where the water body of the flea outbreak, its phytoplankton are eaten by it, so that the water body is particularly thin, the water body is transparent. Knowledgeable people know that this situation is not good, and will use insecticides to eliminate it quickly (that is, the use of enemy insects to kill fleas mentioned above). That is to say, if the water fleas see the outbreak at the beginning of the pond under the water spray, it is a bad thing. Some novice fish farmers think that the water fleas are natural fish feed and are complacent, but they ignore the water flower seedlings that have just gone down to the pond and cannot enjoy it at all.
Make full use of the finger-horned fry, generally after 7-10 days of water fry in the pond, at this time the total length of the fry is about 1 cm, that is, the wuzai fry, which can completely eat the water fleas and other branch-horned plankton, because the water fleas are rich in nutrients, and the fry have a sharp rise process at this stage. The peak period of the branches can be maintained for about one week.
(Harvested water flea red worm)
However, different kinds of splash fish fry have different needs for zooplankton, some special species of fish, such as California perch, catfish, sturgeon, mullet, etc. in the splash nursery stage, because of its special diet, do not eat "human fireworks", egg yolk soy milk has no chance, splash seedlings need to be fed with water fleas zooplankton in the pond, until the artificial domestication feed, which reflects the great role of water fleas, breeding rotifer fleas is crucial to water bloom seedlings.
(California perch seedling fleas)
The methods of breeding zooplankton, including rotifers, introduced above, have included the method of cultivating water fleas, which are omitted here.
Combined with the above, there are three kinds of harmful cases of hydra:
First, when the water and fish fry are in the pond and cannot eat the branches and horns, they grab the material and consume oxygen.
Second, when silver carp fry and other fish fry that feed on phytoplankton are converted to filter feeding, the large number of branches and horns makes it impossible for phytoplankton to reproduce, and the pool water will be seriously hypoxic.
Third, fleas are over-flourishing and consume phytoplankton in the water (because zooplankton faiths feed mainly on phytoplankton), resulting in a lack of plankton for fry to eat when the water flea is strong, and some fish ponds are not baited or insufficient feeding, fry white-headed white-mouth disease is most likely to occur.
(Salvage of fleas)
Combined with the above, rotifers and flea are high-quality natural food for fry, which are widely used in freshwater water bodies, not only have high protein content, but also contain amino acids, vitamins and calcium necessary for fish, and are nutritionally comprehensive and balanced. However, the two have different emphases, rotifers are the best open bait when the water spray seedlings go down to the pond, and water fleas are the natural food that the summer flower seedlings like to eat, these knowledge points need to be fully mastered and fully utilized.
(Liu Wenjun2021.06.26)
See also:
High yield cultivation of water spiders (water fleas): The most suitable natural food for seedlings, which is crucial for water spray seedlings
Traditional cultivation of water splash fry: fry green food--- cooked egg yolk water, raw soy milk feeding method
Briefly describe the feeding method of water and water seedlings: careful before the pond, careful after the pond, the fun is unlimited
Use and control of plankton by aquaculture nursery: zooplankton must be present but not more
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