1. Freshwater fish live in freshwater, while seawater fish live in seawater.
Freshwater fish should pay attention to the PH value of freshwater if they want to keep it well. In the north, especially in Beijing, the water is hard. If they want to keep a kind of delicate freshwater fish, they need to lower the PH value so that the water is acidic. Generally, the resin that reduces the PH value is used.
The water for raising seawater fish is manually allocated. It will remain around PH8.4 after the water quality is stable. Generally, the PH value of water is not adjusted. However, the intensity of light will affect the PH value of seawater. Sometimes it will reach the level of urgency for organisms. However, the PH value of a mature seawater tank will be different because of the role of algae and bacteria. Keep it in a safe area.
Freshwater fish need to change water regularly, which is not stipulated, but changing 1/10 of the water every week is the need for good growth of organisms. Because of the strong filtration system (mainly the high cost of sea water), the frequency and quantity of water change are far lower than that of fresh water, I will not say the specific quantity, because I do not change much water, but this half year I changed half of the water, because a friend made a big tank, I also made a new small tank, so I changed it. Half cylinder of old water, ha-ha.
In contrast, freshwater fish require higher temperatures than seawater fish.
Because in the sea, under the sun at noon, the water temperature may reach 40 degrees, but in the evening, when the sea rises and falls, the cold water can drop the water temperature to more than 20 degrees.
If such a large temperature difference were placed on freshwater fish, it would probably catch a cold in a few days.
In this respect, seawater fish are much more solid than freshwater fish.
3. Disease resistance
Freshwater fish are usually "produced" by fish farms.
Marine fish are basically caught in the wild.
Moreover, in the sea, the living conditions are very bad, all the survivors are "strong", so from the physical point of view, seawater fish is much stronger than freshwater fish.
And the sea water is saltwater, there are not so many bacteria and viruses in fresh water, so long as the water quality is well controlled, the life of marine fish will be very long.
4. Body color
That's not much to say! Marine fish are much more beautiful and weird than freshwater fish.
Many freshwater fish can be artificially reproduced, especially peacocks and other eggs and embryos of fish are very light and can successfully produce the next generation.
But artificial reproduction of ornamental fish in seawater has always been the focus of the aquarium, not without successful examples, but it is really the scales and claws of Phoenix feather.
6. Other organisms
Marine fish farming also includes coral farming. The sea is the cradle of life, and its biological richness is much higher than that of fresh water. You should understand that it is not necessary to elaborate.