Detailed Explanation of Copepod Cultivation Methods and Technical Key Points
How to cultivate copepods?
There are many species of copepods, so species suitable for cultivation should be selected. Suitable species for cultivation should have: strong adaptability to the environment; omnivorous feeding habits, able to feed on plant and animal feed and organic detritus; strong reproductive capacity and fast growth; and high nutritional value as feed for ornamental fish larvae.
(1) Cultivation equipment The main cultivation equipment includes culture containers, stirrers, aeration devices, heating devices, etc.
Small-scale culture containers mostly use plastic tanks of about 1 m. Large-scale culture containers are mostly cement ponds, with capacities ranging from several cubic meters to several hundred cubic meters. Pond depth is generally 1-1.3 m. Small-scale culture containers mostly use air stones for aeration and stirring, without a dedicated stirrer. There are two types of stirrers used for cement ponds: one is a dedicated stirrer with blades, running at low speed, stirring the water body by means of the blades; the other uses plastic pipes laid on the pond bottom for aeration and stirring. Copepods require relatively high water temperatures for growth and reproduction, so heating devices need to be provided.
(2) Treatment of cultivation water The cultivation water should preferably be filtered through sand; if there is no sand filtration equipment, it can also be filtered with sieve cloth netting to remove large animals from the water.
(3) Inoculation There are two ways to obtain the seed stock. One is to collect copepods from natural waters, and after separation and enrichment culture, inoculate them into large-scale culture containers; the other is to collect copepod eggs for hatching. A larger inoculation amount is better. With a large inoculation amount, the time to proliferate to harvestable density is short, and production efficiency is high. The maximum inoculation amount can reach half of the maximum density under the culture conditions at that time.
(4) Placing attachment substrates For cultivating benthic and semi-benthic copepods, attachment substrates need to be placed. For example, Tigriopus japonicus has the habit of crawling on pond walls and bottoms or swimming nearby. To increase its habitat, placing attachment substrates has a clear effect. Types of attachment substrates include mosquito netting, sieve cloth netting, plastic corrugated boards, polyethylene films, etc. Hanging mosquito netting as an attachment substrate will not reduce aeration capacity, and moss grows on the mosquito netting, serving the roles of attachment substrate, feed and water quality stabilization.
(5) Manage ment
① Feeding: suitable feed should be selected according to the feeding habits of the copepods. Omnivorous copepods have many types of feed and are suitable for mass culture. In addition to feed type, the feeding amount must also be controlled. If a plastic tank with a capacity of 1 m is used as the culture container, mixed feeding of shrimp compound feed and yeast: shrimp compound feed is fed at 30-75 grams per week, yeast is fed at 2 grams per day; after 1 week, Tigriopus japonicus proliferates to 14,000-17,000 individuals/L; mixed feeding of fish compound feed and yeast: fish compound feed is fed at 5-10 grams every 2-3 days, yeast is fed at 10 grams every 2-3 days; after 1 week, Tigriopus japonicus proliferates to 16,000-20,000 individuals/L; feeding soy sauce residue 125-625 grams once or multiple times; after 1 week, Tigriopus japonicus proliferates to 4 000 individuals/L.
② Stirring and aeration: the functions of stirring and aeration are, first, to increase dissolved oxygen in the culture water, and second, to prevent feed from sinking; this is an important measure in culture management. However, the intensity of stirring and aeration should be properly controlled. Benthic and semi-benthic copepods have the habit of living near pond walls, and excessive stirring intensity or excessive aeration may have adverse effects on them.
③ Controlling temperature and light intensity Temperature and light intensity should be controlled within the most suitable range. Temperature should not fluctuate too much.
④ Water quality control indicators During copepod culture, water quality changes should not be too large, especially when feeding artificial feed. During the culture process, dissolved oxygen should be greater than 5 mg/L, and pH should be controlled at 7.5-8.6. If dissolved oxygen and pH are too low, aeration should be strengthened.
⑤ Harvesting The maximum density of cultured copepods has a certain limit, and it varies with culture conditions. According to reports, the proliferation density of Tigriopus japonicus is 30,000 individuals/L in a 1-liter tank, 18,000 individuals/L in a 30-liter tank, up to 15,000 individuals/L in a 1 m tank, 36,000 individuals/L in a 40 m pond (using oil yeast as feed), and in a 200 m s pond (using baker's yeast as feed), the proliferation density also reaches 15,800 individuals/L. After the density reaches a certain level, part of them must be harvested, which is beneficial for long-term stable proliferation of copepods. The size of each harvest should be based on not affecting their proliferation. If each harvest is too small, the standing stock will be large, and the copepods will be in a relatively high-density state, which is unfavorable for their growth and reproduction. Conversely, if each harvest is too large, the standing stock will be small, the number of individuals participating in reproduction will be few, and the speed of proliferation will also be affected. Each harvest should preferably be about 10%. The harvesting method is to scoop with a net with a mesh size of 0.33 mm. The harvested individuals are mainly adults and late-stage larvae.
(1) Cultivation equipment The main cultivation equipment includes culture containers, stirrers, aeration devices, heating devices, etc.
Small-scale culture containers mostly use plastic tanks of about 1 m. Large-scale culture containers are mostly cement ponds, with capacities ranging from several cubic meters to several hundred cubic meters. Pond depth is generally 1-1.3 m. Small-scale culture containers mostly use air stones for aeration and stirring, without a dedicated stirrer. There are two types of stirrers used for cement ponds: one is a dedicated stirrer with blades, running at low speed, stirring the water body by means of the blades; the other uses plastic pipes laid on the pond bottom for aeration and stirring. Copepods require relatively high water temperatures for growth and reproduction, so heating devices need to be provided.
(2) Treatment of cultivation water The cultivation water should preferably be filtered through sand; if there is no sand filtration equipment, it can also be filtered with sieve cloth netting to remove large animals from the water.
(3) Inoculation There are two ways to obtain the seed stock. One is to collect copepods from natural waters, and after separation and enrichment culture, inoculate them into large-scale culture containers; the other is to collect copepod eggs for hatching. A larger inoculation amount is better. With a large inoculation amount, the time to proliferate to harvestable density is short, and production efficiency is high. The maximum inoculation amount can reach half of the maximum density under the culture conditions at that time.
(4) Placing attachment substrates For cultivating benthic and semi-benthic copepods, attachment substrates need to be placed. For example, Tigriopus japonicus has the habit of crawling on pond walls and bottoms or swimming nearby. To increase its habitat, placing attachment substrates has a clear effect. Types of attachment substrates include mosquito netting, sieve cloth netting, plastic corrugated boards, polyethylene films, etc. Hanging mosquito netting as an attachment substrate will not reduce aeration capacity, and moss grows on the mosquito netting, serving the roles of attachment substrate, feed and water quality stabilization.
(5) Manage ment
① Feeding: suitable feed should be selected according to the feeding habits of the copepods. Omnivorous copepods have many types of feed and are suitable for mass culture. In addition to feed type, the feeding amount must also be controlled. If a plastic tank with a capacity of 1 m is used as the culture container, mixed feeding of shrimp compound feed and yeast: shrimp compound feed is fed at 30-75 grams per week, yeast is fed at 2 grams per day; after 1 week, Tigriopus japonicus proliferates to 14,000-17,000 individuals/L; mixed feeding of fish compound feed and yeast: fish compound feed is fed at 5-10 grams every 2-3 days, yeast is fed at 10 grams every 2-3 days; after 1 week, Tigriopus japonicus proliferates to 16,000-20,000 individuals/L; feeding soy sauce residue 125-625 grams once or multiple times; after 1 week, Tigriopus japonicus proliferates to 4 000 individuals/L.
② Stirring and aeration: the functions of stirring and aeration are, first, to increase dissolved oxygen in the culture water, and second, to prevent feed from sinking; this is an important measure in culture management. However, the intensity of stirring and aeration should be properly controlled. Benthic and semi-benthic copepods have the habit of living near pond walls, and excessive stirring intensity or excessive aeration may have adverse effects on them.
③ Controlling temperature and light intensity Temperature and light intensity should be controlled within the most suitable range. Temperature should not fluctuate too much.
④ Water quality control indicators During copepod culture, water quality changes should not be too large, especially when feeding artificial feed. During the culture process, dissolved oxygen should be greater than 5 mg/L, and pH should be controlled at 7.5-8.6. If dissolved oxygen and pH are too low, aeration should be strengthened.
⑤ Harvesting The maximum density of cultured copepods has a certain limit, and it varies with culture conditions. According to reports, the proliferation density of Tigriopus japonicus is 30,000 individuals/L in a 1-liter tank, 18,000 individuals/L in a 30-liter tank, up to 15,000 individuals/L in a 1 m tank, 36,000 individuals/L in a 40 m pond (using oil yeast as feed), and in a 200 m s pond (using baker's yeast as feed), the proliferation density also reaches 15,800 individuals/L. After the density reaches a certain level, part of them must be harvested, which is beneficial for long-term stable proliferation of copepods. The size of each harvest should be based on not affecting their proliferation. If each harvest is too small, the standing stock will be large, and the copepods will be in a relatively high-density state, which is unfavorable for their growth and reproduction. Conversely, if each harvest is too large, the standing stock will be small, the number of individuals participating in reproduction will be few, and the speed of proliferation will also be affected. Each harvest should preferably be about 10%. The harvesting method is to scoop with a net with a mesh size of 0.33 mm. The harvested individuals are mainly adults and late-stage larvae.