CATDOLL : CATDOLL: Why tropical fish can't be kept with freshwater fish

Why can't tropical fish be kept together with freshwater fish?

Why can't tropical fish be kept together with cold water fish?

Because tropical fish are also a type of freshwater fish.

1-Goldfish and koi are both cold-water fish, and their suitable water temperature is different from that of tropical fish.

2-You can raise them together. However, most tropical fish will peck at goldfish, so you must choose tropical fish with docile temperament to raise them together.

Why can't marine fish and freshwater fish be kept together?

Theorem 1: Solutions with high concentrations diffuse toward areas with low concentrations.

Marine fish: The salinity of the cell solution is lower than that of seawater, so the body is constantly losing water, so it absorbs a large amount of water from seawater to replenish water (with the help of the kidneys)

Freshwater fish: The salinity of the cell solution is greater than that of fresh water, so the body is constantly filled with water, and the kidneys are used to drain it.

See for yourself what happens to freshwater fish when they enter seawater, because their kidneys function differently.