CATDOLL : CATDOLL: How to raise China’s four major carps?

1. How to raise China’s four major carps?

China's four major carps are mackerel, grass carp, silver carp and bighead carp.

2. Why does duckweed kill fish?

Too much duckweed will consume oxygen in the water, causing fish to lack oxygen. Haha, I don't need to tell you the consequences. This is not just duckweed. Too much other aquatic plants and insufficient oxygen will also cause this situation.

3. How to remove duckweed in fish ponds

There are three ways to remove duckweed from fish ponds:

4.What is duckweed?

. The ventral surface is light green to gray-green, and the dorsal surface is brown-green to purple-brown. The ones with green color, purple back, dry, complete and free of impurities are preferred. Green duckweed: Also known as green-backed duckweed. The fronds are green on both the ventral and dorsal surfaces. The ones with green color, dry, complete and free of impurities are preferred.

Spirogyra, a perennial small herb, floating on the water surface. Roots 5-11 in bundles, thin, fibrous,

duckweed

3-5cm long. New shoots are produced on one side of the root attachment, and are connected to the mother plant by a thin stalk before they separate. The thallus is flat, solitary or clustered in 2-5, broadly obovate, 4-10mm long, 4-6mm wide, obtuse at the apex, slightly concave above, dark green, purple below, with 5-11 inconspicuous palmate veins. The inflorescence grows in the notch on the edge of the thallus; the flowers are herbaceous, and the hermaphrodite is monoecious; the spathe is bag-shaped, short, 2-lipped, with 2 male flowers and 1 female flower, without perianth; the male flower has 2 stamens, 2 anthers, and slender filaments; the female flower has 1 pistil, sessile ovary, 1-chamber, with 2 erect ovules, short style, flat or annular stigma. The fruit is round with wings on the edge.

Flowering period is April-June, and fruiting period is May-July. Duckweed, a small floating herb. There is one root, 3-4cm long, slender, the root sheath is wingless, and the root crown is obtuse or truncated. The thallus is symmetrical, obovate, elliptical or nearly round, 1.5-6mm long, 2-3mm wide, smooth, green, opaque on the upper surface, light yellow or purple on the lower surface, all-line, with inconspicuous 3 veins. There is a capsule on one side of the back of the thallus, and the new thallus is formed in the capsule and floats out, connected to the mother body by a very short stalk, and then falls off. The flowers are unisexual, monoecious, and born at the cracks on the edge of the thallus; the spathe is wing-shaped, with 1 female flower and 2 male flowers; the male flower has 2 anthers, and the filaments are slender; the female flower has 1 pistil, and the ovary is giant, with 1 curved ovule. The fruit is nearly gyroid-shaped and wingless. There is 1 seed with a raised endosperm and 12-15 irregular convex veins.

5. What are the names of these two types of water plants? They grow in ponds and are quite common.

duckweed

Lemna minor L.

Lemnaceae

Alias: Duckweed floating grass floating duckweed grass Labsaga green floating green floating rice floating duckweed grass green duckweed green duckweed grass water duckweed water flower duckweed duckweed grass field duckweed small duckweed green duckweed water grass purple duckweed

6. There are i dominant species in a pond, namely bighead carp, zooplankton and phytoplankton. Bighead carp feeds on zooplankton, and zooplankton feeds on phytoplankton.

A. If too much fertilizer is applied to the pond, eutrophication will cause algae to multiply, which will lead to lack of oxygen in the water and the death of a large number of animals. A is correct.

4. A decrease in the number of bighead carp will increase the number of zooplankton, which will in turn lead to a decrease in the number of phytoplankton. 4 is wrong;

C. According to the relevant knowledge of energy flow and interspecific relationships, in order to increase the production of bighead carp in the pond, two methods can be used: reducing the number of its competitors and predators or increasing its food sources. C is wrong.

The introduction of wild fish increases the complexity of the nutritional structure of the ecosystem and can improve the efficiency of energy utilization, but it cannot increase the efficiency of energy transfer between trophic levels. This is wrong.

Therefore, the answer is: A.