Poisonous fish are fish that can make you sick or hurt you if you eat or touch them. It's like when your mom tells you not to touch the hot stove or eat something that looks yucky because you might get sick.
There are a few different ways fish can be poisonous. Some fish have venomous spines or fins that can poke you and cause a lot of pain. Other fish have toxins in their flesh or organs that can make you sick if you eat them.
One type of fish that can be poisonous is the pufferfish. Pufferfish have spikes filled with poison that they can use to defend themselves. If a person eats a pufferfish that hasn't been prepared correctly, they can get really sick and even die. That's why chefs who prepare pufferfish have to be specially trained so they know how to remove the poison safely.
Another type of poisonous fish is the lionfish. Lionfish are beautiful with their bright colors and long fins, but if you touch their spines, you can get a painful sting. The sting can even be dangerous for some people and cause an allergic reaction.
So, it's important to be careful around fish that might be poisonous. Don't touch or eat them unless you know it's safe. And always listen to your parents or grown-ups when they tell you something might be dangerous!