they are both fish?
no
they are both saltwater and freshwater
They contain saltwater and freshwater
No, the sun will not heat saltwater and freshwater at the same rate. Saltwater has a higher density and specific heat capacity than freshwater, meaning it requires more energy to raise its temperature. As a result, saltwater generally heats up more slowly than freshwater when exposed to the same amount of sunlight. This difference can lead to varying temperature profiles in aquatic environments.
A freshwater fish cannot be with a saltwater fish.It depends on the fish. Guppies are considered "freshwater" but will live happily in SW if properly acclimatized. Mollies are the same way.
It doesn't make a difference weather it is saltwater or freshwater because they will cool at the same rate it is just that when saltwater evaporates it will leave the salt particles behind.
No
The same as in the ocean
Lobsters are saltwater and crayfish (crawdads) are freshwater.
The Persian Gulf is saltwater, not freshwater.
Saltwater is heavier because saltwater contains salt which adds to its overall weight. Freshwater does not have any dissolved salt so it is lighter then saltwater
Most lakes contain freshwater. From this fact, I'm assuming it is made out of freshwater, rather than saltwater.