three-spined stickleback

The three-spined stickleback (Gasterosteus aculeatus) is a small fish, typically 2 to 4 inches long, found in fresh and saltwater environments across the Northern Hemisphere. It is characterized by a row of three dorsal spines, a sharp spine on each pelvic fin, and bony plates on its sides instead of scales.12

Sticklebacks are known for their unique breeding behavior. The male, often displaying vibrant colors during mating season, builds a nest from plant materials. He then guides females into the nest to lay their eggs, which he fertilizes. The male diligently guards and aerates the eggs until they hatch, and protects the young from predators. This parental care is a defining trait for most stickleback species.1