After adding salt to the fish tank, it is necessary to pay attention to the problem of changing water. The salt in the fish tank can inhibit the reproduction and disinfection of bacteria. Generally speaking, after adding salt, you can wait 2 or 3 days to change the water. After adding salt, it doesn't mean that you don't need to change water, and you can't change water for a long time. The problem of changing water also needs attention. Generally speaking, you can change a quarter of the whole water, but you can't change it all.