Fishes are aquatic animals that typically have gills, fins, and a streamlined body. They are found in both freshwater and saltwater environments around the world. Fishes belong to the phylum Chordata and are classified into various groups, including bony fishes and cartilaginous fishes. They play a crucial role in aquatic ecosystems and are an important food source for many animals, including humans. Fishes breathe by extracting oxygen from water through their gills. They come in a wide range of sizes, shapes, and colors, with some species being very small, like the paedocypris, while others, like the whale shark, can grow to be enormous. Fishes reproduce in various ways, with some laying eggs and others giving birth to live young.