The fish tank is not cleaned up: generally, only one third or one quarter of the water will be replaced. If the impurities in the fish tank are not cleaned up, the water will still emit a fishy smell after changing the water. There is no filtering system in the fish tank: if there is no powerful filtering system in the fish tank, the new water is easy to be polluted and give off a fishy smell after changing the water. Fish is sick: if the fish is sick and has not been treated, the water will be fishy even if the water is changed. 1、 Why is the freshly changed water fishy? In the process of fish culture, the water may emit fishy smell, and even the freshly changed water may have fishy smell. Specifically, there are the following reasons:
1. The aquarium is not cleaned up: we may only replace a third or a quarter of it every time we change water. In this case, if the feces and food residues in the fish tank are not cleaned up, the water will still emit a fishy smell after changing the water.
2. There is no filter system in the fish tank: in addition, it may be because there is no filter system in the fish tank or the function of the filter system is not good. In this case, the newly changed water is also easy to be polluted by fish excreta, and then it will give off a fishy smell.
3. Fish sick: there may be fish sick. In this case, even if the water is changed, it is easy to emit a fishy smell because the disease of fish has not been cured. 2、 Can salt solve the fishy smell in the aquarium? After the fishy smell in the aquarium, you can use some substances to reduce or eliminate the fishy smell in the aquarium. Salt is a substance we often use. After changing the water, you can sprinkle a little salt, but not too much. The concentration of salt in the water can't be too high. At the same time, the fish tank can be exposed to light for a period of time every day. In addition to salts, there are some substances that can be used. They also have the effect of removing fishy smell, such as vinegar. Some special substances, such as chlorine dioxide effervescent tablets, can be tried. （YuGangGangHuanDeShuiWeiShenMeXing，YanNengJieJueYuGangDeXingWeiMe）