There are approximately 32,000 different kinds of fish in the world today, which is more than all the other kinds of vertebrates combined. Scientists are discovering new species all the time. With so many fish in the world, why not learn a few interesting facts.
1. It’s difficult to determine how fast some fish can swim, but some anglers at Florida’s Long Key Fishing Camp came up with a simple method for accurately measuring a fish’s swimming speed. A fish is hooked. It makes a run. You measure how much line the fish takes off the spool in a certain number of seconds, and you can calculate the fish’s speed. The fastest fish is the sailfish. It can swim as fast as a car travels on the highway.
2. Sometimes tornadoes pick up fish while traveling over water and carry them over land, where the fish rain down. These “fish showers” have been happening for thousands of years. Roman writer Pliny the Younger describes this phenomenon in the 1st century A.D.3. The slowest fish a seahorse. It swims so slowly that a person can barely tell it is moving. The slowest is the Dwarf Seahorse, which takes about one hour to travel five feet. It even looks like it is simply standing up, not swimming.
4. Humans have been amazed for centuries that salmon, after journeying across the ocean, can find the river where they were born. In the Yukon River in Alaska and in Canada, certain tagged Chinook salmon covered nearly 2,000 miles in 60 days. Salmon also have adapted to live in a variety of aquatic environments, including rivers, lakes, estuaries, coral reefs, and the open sea. 
5. Fish would suffocate if they tried to chew because chewing would interfere with water passing over their gills.
4. Humans have been amazed for centuries that salmon, after journeying across the ocean, can find the river where they were born. In the Yukon River in Alaska and in Canada, certain tagged Chinook salmon covered nearly 2,000 miles in 60 days. Salmon also have adapted to live in a variety of aquatic environments, including rivers, lakes, estuaries, coral reefs, and the open sea. 
5. Fish would suffocate if they tried to chew because chewing would interfere with water passing over their gills.6. The word “piranha” is from the Tupi (Brazil) pira nya and means “scissors.” Found in freshwater rivers in South America, piranhas have razor-sharp teeth. They typically eat fish, insects, seeds, fruit, and even larger animals such as horses. While there are no proven reports of piranhas killing a person, they do eat human carcasses. 
7. Fish use a variety of low-pitched sounds to convey messages to each other. They moan, grunt, croak, boom, hiss, whistle, creak, shriek, and wail. They rattle their bones and gnash their teeth. However, fish do not have vocal chords. They use other parts of their bodies to make noises, such as vibrating muscles against their swim bladder.
7. Fish use a variety of low-pitched sounds to convey messages to each other. They moan, grunt, croak, boom, hiss, whistle, creak, shriek, and wail. They rattle their bones and gnash their teeth. However, fish do not have vocal chords. They use other parts of their bodies to make noises, such as vibrating muscles against their swim bladder.8. Researchers studying walleye vision found that orange is the color most visible to walleyes, followed by yellow and yellow-green. Surprisingly, red is the least visible color. No wonder you find so many orange and chartreuse lures in the tackle boxes of savvy walleye anglers.
9. Unlike bony fish, sharks and rays do not have swim bladders. They have to swim all the time, even when they are sleeping. Otherwise, they will sink to the bottom of the ocean.
10. 40% of all fish species inhabit fresh water, yet less than .01% of the earth's water is fresh water.