About Different Fish Species

There are many different species of fish on the planet. They range from nearly microscopic size, to huge fish that weigh hundreds of pounds. Fish can be found in any sort of water from oceans to lakes, ponds, streams and rivers to even the total darkness of caves.

What Makes a Fish?

There are other creatures that live in the water that are not fish. A good example are whales and dolphins. They may look like fish but they breathe air and have hair, so they are actually mammals. Fish have scales and breathe through their gills. Another feature that fish have is secretion of a mucus that helps protect them from parasites and disease. This mucus is what causes a fish to feel slimy to the touch. Another factor differentiating fish from other animals is that they are vertebrates, which means that they have a backbone.

The Difference between Saltwater and Freshwater Fish Species

There are two distinct species of fish. Those that live in saltwater, also known as marine fish, and those who live in freshwater. Some of the main differences between freshwater and marine fish are the water they live in, but there are other differences. Marine fish obviously have a different diet than freshwater. There is the parrotfish that has a mouth designed for breaking open the shells of clams. Also, the remora, a fish designed to attach itself to other marine animals and eat the parasites living on it. Some marine fish are very colorful, and have colors not found in freshwater fish. Although, there are some very large freshwater fish, generally, the largest fish species will be found in the ocean.