Betta fish, commonly known as Siamese fighting fish, are one of the most popular and well-known freshwater fish species kept as pets. Their vibrant colors, ornate fins, and minimal care requirements make them popular among both rookie and veteran aquarists. In this chapter, we'll look at the interesting world of Betta fish, including their origins, distinguishing qualities, and why they make such attractive pets. Origin and History Betta fish (Betta splendens) are endemic to Southeast Asia, particularly Thailand, Laos, Cambodia, and Vietnam. They live in shallow, slow-moving waterways like rice paddies, ponds, and marshes. The fish have been grown and preserved in this area for years, originally for use in traditional fish fighting. Historically, these bouts were not only a source of entertainment, but also an opportunity for owners to display the quality and power of their fish. The moniker "Betta" comes from the Thai word "bettah," which means "strife" or "battle," referring to the fish's aggressive temperament. Betta fish were imported to Europe in the nineteenth century and then to the United States, where they were acclaimed for their beauty and became popular decorative pets. Physical characteristics Betta fish are known for their bright colors and intricate fin displays. They come in a range of hues, including red, blue, green, purple, and white, and may be solid, marbled, or multicolored. Betta fish are known for their long, flowing fins. Males, in particular, are famed for their stunning fin displays during courting and territorial fights. Betta fish have a distinct anatomical feature known as the labyrinth organ. This particular anatomy enables them to breathe air from the surface, making them ideal for areas with low oxygen levels. This adaptability is a major reason why Betta fish may flourish in smaller tanks or even bowls, while a bigger, well-maintained aquarium is recommended for their general health and wellbeing. Behavior and Temperament Betta fish are noted for their territorial and even violent behavior, particularly in males. In the wild, they build and defend their territories, resulting in frequent conflicts with other males. This territoriality translates into their behavior in captivity; males are often violent against one another, which is why they are typically kept alone or with carefully chosen tank mates.