Pond fish farming in China is characterized by fertilizer water, dense culture and polyculture, because the dissolved organic matter and nutrient salts in the water are very rich, the amount of phytoplankton is very high, the water color is thick, and sometimes there are algae masses, floating membranes, etc., that is to say, there are often blooms. Through the survey and statistics of common blooms across the country, it can be divided into 15 basic types according to the dominant types.
In the long-term production practice, China's fishermen and farmers have accumulated valuable experience in "watching the water and raising fish", the essence of which is to observe the color, appearance and changes of the water bloom. There have been some fragmentary reports on the relationship between water color and phytoplankton species. It is generally believed that the cells of golden algae, yellow algae, diatoms and dinoflagellates are brown or brownish green, and their blooms are close to the above colors; green algae and naked algae cells are green, and their blooms are also close to green; cyanobacterial cells are dark green or dark blue. Its blooms are also close to dark green or blue-green.
However, the reality is much more complex.
First of all, although the same phylum algae have their commonality in pigment composition, there are special cases, such as cyanobacteria species are generally blue-green or gray-green, while some species (Mongeritic algae, mud brown mat algae, etc.) because of the content of more melasmin (caribrin and lutein) and red pigment (phycotein) and make the cells appear melasma, reddish brown and purple and other colors; naked algae are usually green, but there is a large amount of heme in the blood red nude algae and cells to make the water reddish brown; some algae have cyst shells, so that the water is shelled, the color of the shell and nail.
In addition, the pigment composition of the same species can also change when living conditions change, especially cyanobacteria and green algae, when the population growth reaches the end of the exponential growth period, often due to insufficient nutrients (nitrogen, phosphorus, carbon or trace elements) or other reasons to cause the cells to "aging" phenomenon, when chlorophyll decreases and the amount of caribrin and lutein increases, so that the algae yellow or brown.
The phenomenon of changing the color of various algae to adapt to light conditions is more widespread. It has been observed that the blooms of golden algae, diatoms, cryptoalgae and dinoflagellates are almost all brown, brownish green or brownish blue, while the blooms of cyanobacteria, green algae and naked algae are not only green and blue-green, especially cyanobacteria may occupy a larger number in almost all kinds of water colors.
It can be seen that it is difficult to distinguish the composition of plankton simply from the color of water, and the quality of water is not only a matter of species composition.
(1) Cryptoalgae blooms.
This is a common bloom in pond fish farming in China, and its frequency of occurrence can reach 80% to 100% in fertile water everywhere, and the sub-dominant species are often called some species of small ring algae, cyanobacterial algae and chlorella. Aqua brown, reddish brown, brown green and brownish green. Available all year round.
(2) Knee-oral algae blooms.
In fish ponds, the most common bloom after summer fertilization occurs, occurring at nearly 60% frequency during the growing season. The dominant species are oblate knee-mouth algae, the sub-dominant species are cryptoflagellum and psilocyces, and sometimes there are more chlorella, aquamarine or brownish green.
(3) Psilocybinoid algae blooms.
This is caused by the proliferation of blue-green beetles, which are more common in fertile water and occur more often in summer and autumn. In summer, it grows in coexistence with the oblate knee-mussel algae. The water color is brownish green, brownish blue or iron gray, and the water surface has cloud-like blue-green spots, which fishermen call "turning water".
(4) Horn algae blooms.
Sometimes seen in carp ponds, the dominant species is the flying swallow horned algae, the water color is uneven yellow-brown, and the thick brown patches formed by the flying swallow algae clusters can be seen.
(5) Fibrillator or mat algae blooms.
Blooms formed by certain species of the genus Algae or Algae. The aqua color is blue-green to gray-green, but individual species can cause a special water color, such as the bloom of the Eropus algae is often yellowish brown, the reddish trilled algae bloom is red, and the mud brown mat algae bloom is reddish brown. It occurs mostly in the summer.
(6) Ichthyosaurus or ichthyophytes blooms.
Blooms caused by spirulina or other ichthymatous algae species and ichthymatoids. The dominant species is extremely prominent, accounting for more than 95% of the total biomass, aqua blue-green or dark green, visible emerald green yarn or blue-green floating film. Appears in summer.
(7) Microcystic algae blooms.
The dominant species are microcystis aeruginosa and powdery microcystis, aqua blue-green, dark green or yellow-green whitish. Microcystis aeruginosa often has a blue-green or yellow-green floating membrane on the surface of the water, which occurs mainly in summer.
(8) Tip-headed algae blooms.
The water color is blue-green or yellow-green, and the water surface often has a floating film, which appears in summer or early autumn.
(9) Micro-cyanobacteria blooms.
Blooms caused by some very miniature species of Cyanophylla. Dominant species are often chlorella (Chroococfus), stick algae, cyanofiber algae, sticky chlorella and flat schizophores, and the water color is dark green, blue-green, brown-green, brownish and yellow-brown.
(10) Clugae blooms.
Blooms usually formed by Chlamydia, Tetraflagellum, Hollow Bulbophyllum and Solid Bulbophyllum, etc., are also abundant in cryptogagae and other flagella species. The water color is green, and the water surface often has a green floating film.
(11) Chlorella blooms.
Usually composed of chlorella, gravis, tetragonal algae, cruciferous algae, chlorella and hollow algae, etc. formed by blooms, dinoflagellates such as yin algae and small ring algae account for a certain amount, the water color is green or yellow-green, the transparency is large, easy to appear in shallow water and often fertilized fish ponds.
(12) Naked algae blooms.
Blooms are formed mainly by red naked algae, and the number of cryptogae and other flagella is usually also higher. The aqua green is red, green or reddish brown, and the water surface usually has a red floating film.
(13) Cystic bare algae blooms.
Blooms are usually formed by the likes of Echinaceous Sac Naked Algae and Rotational Sac Naked Algae, etc., and the surface of the water is soot or reddish-brown.
(14) Diatom blooms.
Blooms are formed mainly by small ring algae, pintail algae, boat-shaped algae and rhomboid algae. Cryptococcus and chlorella chlorococcus are also usually found in larger numbers. Aqua brown with greater transparency. Mostly appear in the spring and autumn.
(15) Golden algae blooms.
Blooms are often formed by brown flagella and monoflagellum, and usually more diatoms and cryptoalgae. The water color is golden brown with greater transparency. Occurs mainly in early spring.
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