Why do crab seedlings catch grass in the pond?

From seedling stage to adult stage, crabs keep eating tender grass, and tender grass keeps growing, which is the balance between ecology and nature. When the temperature rises, the growth rate of crab grass such as Elodea nuttallii and Ceratophyllum japonicum exceeds that of crabs, and the grass will multiply in large numbers until the stems are hard and unpalatable, and the crabs will decline in autumn, and the crabs will grow in a balanced way. The premise is to plant grass at a suitable density, otherwise the grass roots and seeds must be replanted if they are eaten by crab seedlings.

Crab farming generally adopts two-stage stocking to solve the problem of young grass being caught. That is, when the grass grows to more than 20cm, small-scale captive crab seedlings are released; During this period, the crab seedlings grow normally and one shell is completed without delay.