Decaying leaf litter - the water appears black in tropical regions because of this. It also makes the sea where the river mouth is "muddy" and not look like tropical water- this is one of the reasons why coral cannot grow all over the place in equatorial regions
Tropical refers to the temperature of the water; aquariums can be tropical and hard, or tropical and soft water. Water hardness is simply a measure of the mineral content of the water.
no tropical fish need warm water
no tropical water means the fish are found in tropical regions which means the water is warm - 21-28 Cece's
These spectacular fish (Pseudanthias species) are tropical marine (salt water) fish.
Subtropical water is cold water that is not tropical.
"Tropical" simply means the aquarium is kept above 60F. "Marine" simply means the water in the aquarium has had sea salt added to make the water into sea water. Therefore it is possible to have aquaria that are "Tropical", or "Marine", and also "Tropical marine".
There are a couple of ways to define what are tropical waters. The first is:- By geographical position, any water that lies between the Tropic of Cancer in the Northern Hemisphere and the Tropic of Capricorn in the Southern Hemisphere must be Tropical Waters. The other way to define Tropical Water is subjective and dependent on temperature. In my opinion tropical water is water that never goes below 65F.
Fresh Water
Subtropical water is cold water that is not tropical.
you can tell by the labal at the pet store you get it from and also by the temperature of the water in your tank. for example,a goldfish is not tropical. therefore it needs cold water. a guppy is tropical,so it needs warm water
Some catfish species are tropical and others are cold water.
There are a couple of things you can do to control the pH of the water for tropical fish. You can for example drain the water and start over.