Aquatic bacteria are microorganisms that live in water environments, including oceans, rivers, lakes, and ponds. They play a crucial role in the ecosystem by breaking down organic matter, recycling nutrients, and supporting the food web. These bacteria can be found in both freshwater and saltwater, adapting to various conditions. These bacteria come in many shapes and sizes, and they can be beneficial or harmful. Some aquatic bacteria, like Nitrosomonas, help convert ammonia into nitrites, which is essential for aquatic plants. Others, such as Vibrio cholerae, can cause diseases in humans and animals. Understanding aquatic bacteria is vital for maintaining healthy water ecosystems.