Tap water on the line, the sun is better, crucian carp on the water quality is not too high requirements, to do a larger tank or ceramic pot, crucian carp on the oxygen requirements are still relatively high (although better than the goldfish), but pay attention to the density of fish and the volume of the container, it is best to have a filtration system, there is no best equipped with an oxygen pump, there is no equipment for three days of a water change, each time two thirds of the filtered water change once every five to seven days, one half or two thirds of the water, and one half of the water. Each time one-half or two-thirds. Feed goldfish dry feed on the line, do not recommend feeding live food, feed live food to pay attention to the health to be washed before feeding