What is the name of fish that are spikes?

Why do we over fish? What are these worms in my turtle tank they are barely visible white and dont appear to be able to swim as they kind of just wiggle around on the bottom I found probably a couple hundred of them? What is the Difference between a school and shoal of fish? How do you know when your fighting fish is pregnant? What species is a mermaid? Where is the mouth of the jellyfish? What are the names of the 12 mermaids you can collect from mermaid magic fizz and surprise? What color goes good with fluorescent yellow? What is a telelosts? Is shark urine cold? What are elvers? What are 3 kinds of small fish? Why DO seahorses MATE? What type of Glass for aquarium? How many babies do neon tetra fish have at once? What can you do to help prevent overfishing? How are fish in ponds that have not been stocked? What are 5 facts about horn pond? How long do rodeo bulls live? How old do you have to be to use plenty of fish?