Goldfish is a traditional ornamental fish in China, and there have been records of its cultivation since the Jin Dynasty. Most people's understanding of this fish is grass gold, or a dragon with big eyes, but in fact its species is very complex. In addition to the grass species and dragon species mentioned above, there are also cultural species and egg species, a total of four categories. In addition, the color of goldfish is also very rich, red, orange, blue, purple, silver, ink and so on. The requirement of dissolved oxygen for this kind of fish is not less than 1 mg per liter, otherwise it will float, and it will also affect discoloration.
Mandrake is a tropical fish of the family Lupodidae, the genus Haliopoda. There are two common species, one is blue mandrake, and the other is yellow mandrake. Apart from the body color, the difference is not very big. This kind of fish does not require high water quality, and when the oxygen content in the water is low, it can float on the surface for ventilation, so it can live without oxygen. However, for the sake of the health of the fish, it is better to fill some oxygen.
The betta and the mandrake are both members of the family Crepidae, but it is a small tropical fish of the genus Bettas. The fish, less than 10 centimeters long, is an omnivorous fish that feeds mainly on plankton, insect larvae and algae. It has a special auxiliary respiratory organ, which can breathe in the air, so it can survive in a low dissolved oxygen environment. However, it should be noted that its temperament is rough, even with the same kind of breeding together, to the breeding period will fight.
Pearl horse turtle is native to Southeast Asia. This kind of fish is silver-gray in color and has pearl-shaped round spots on its body. It is not only very beautiful, but also very easy to keep. With the above two kinds of fish, it can swallow air at the surface, so it can grow in a low dissolved oxygen environment. Moreover, it does not choose food, and can be fed live bait or dry feed.
