Thousands.
Tropical fish have adaptations such as bright colors for camouflage and attracting mates, streamlined body shapes for efficient swimming in warm waters, and specialized gills for extracting oxygen from low-oxygen environments. Additionally, some tropical fish have evolved unique behaviors to avoid predators or to find food in their specific habitat.
Thousands of different tropical fish.
The use many different colors to give the fish a verity of things. For example you don't always eat the same different thing you like a verity. So do fish.
72 legs A tropical fish has 72 legs
There are many different species but I can say that they will all be "Tropical fish"
There are about 40 different species native to various tropical waters
They can be many different shapes and sizes and colors and etc.
there are many colour fish have
The simple answer is that they have evolved with what they require for survival in their particular habitat. In many cases it is for the purpose of defensive/offensive camouflage Sometimes the brilliant colours are for display to attract a partner.
Tropical and brackish are not mutually exclusive. Tropical means warm, and brackish means somewhat salty. Many brackish fish ARE tropical, and many tropical fish are brackish. You can keep tropical brackish fish with other tropical brackish fish, if they have the same temperment and will not harm or eat eachother. You can keep some brackish fish with some freshwater tropicals, and similarly you can keep some brackish fish with some marine tropicals. There are no wide open set of principles for brackish fish compatability beyond those that I have just illustrated.
There are many different kinds of fish that live around the Bahamas. These fish are considered tropical salt water fish.
Mollies make great additons to a tropical fish community tank. They come in many shapes and colors and even breed semi-easily and are very entertaining to watch. Need some info on them: http://slacker1202.tripod.com/id14.html