The most common freshwater fish is the goldfish (Carassius auratus). Originally bred for aquariums and ornamental purposes, goldfish are now found in various environments around the world due to their hardiness and adaptability. They are often kept as pets and are known for their vibrant colors and captivating behavior. Goldfish can vary in size, with some varieties growing up to 12 inches long. Their popularity and availability make them a staple in both home aquariums and outdoor ponds. Additionally, goldfish play a role in cultural symbolism and are often associated with good fortune and prosperity.