When planning your fish tank, it’s crucial to understand the types of water than different species need. That’s why people ofter ask the question “are goldfish freshwater fish”, as they don’t want to put their goldfish into the wrong type of water. To do so would be fatal!
The answer is that goldfish are freshwater fish. This means their bodies are adapted to living in fresh water environments, such as lakes and rivers, which have very low salt concentrations.
Can goldfish live in salt water?
Due to their physiology, goldfish cannot survive in salt water. A process call osmosis causes water with low concentrations of salt to flow through “semipermeable membranes” (such as the cells in a goldfish’s body) to surrounding water with a higher concentration of salt (such as the ocean).
So, if you put a goldfish in salt water, the water from within the fish’s cells would begin to move out of the fish’s body and into the surrounding ocean water. This would cause the goldfish to become critical dehydrated and the fish would quickly die.