Freshwater ray, from the name, I believe it is hard to tolerate salinity, but some people think that adding salt to water is necessary for the health of freshwater ray. Freshwater ray has no glands for salt metabolism, so some people think it is unbearable, while others think that shippers usually add salt to the water containing fish. In fact, businessmen engaged in tropical fish fishing or exporting in Latin America and China will use a large amount of salt when delivering. This practice has also produced the conclusions of different factions: First, this practice is the reason why imported freshwater rays always maintain a certain mortality rate, but exporters in the producing areas firmly believe that this is the way to avoid a large number of deaths. In fact, fish stay in the exporter's facilities for only a few days, not more than a week at most. The toxicity caused by short-term high-concentration salt in a few days will be far lower than that caused by long-term stay of rays in low-concentration water. Many aquarium professionals suggest that the standard of high salt is about 0.3%~0.5%.

The real biggest reason for the use of salt lies in the prevention of urgent factors: the salt contained in fish blood and fresh water is different, and the concentration of NaCl in fish blood is much higher than that in ordinary fresh water. So there will be a mechanism to maintain salinity balance in the preliminaries. This effect is an efficient use of energy, aiming at maintaining high content of sodium chloride in serum. If salt is added to the water, it will reduce or even change the progress of this biochemical mechanism. In this way, the energy required for this energy will be reduced, and if the salinity with too high concentration is used, the pressure of the fish's osmotic membrane will be reduced, so that the equilibrium reaction rate of NaCl ion fluctuation in the water of blood fish environment will be reduced, and the urgent factor of ray fish will be produced.

Therefore, although it is acceptable to add salt to the water of freshwater rays, it is necessary to avoid excessive use and avoid diseases caused by inadaptability. In a word, it is a better way to raise freshwater rays without salt.

For the bacteria in the aquarium, it masks a highly bactericidal compound. Although it can not cure bacterial infection, it can reduce the possibility of spread. Reducing salinity is safe for all fish. According to foreign literature, the safe measurement is that 2~3 grams of salt is added 1 liter of water, and the feeding ratio is maintained at about 0.2%~0.25%.