Which of the following is a common freshwater fish kept in aquariums?

The option selected identifies the Betta fish as a common freshwater fish kept in aquariums. Bettas, known for their vibrant colors and flowing fins, are popular among aquarium enthusiasts due to their hardiness and relatively simple care requirements. They have unique behaviors and can thrive in smaller tanks, making them ideal for home aquariums. Additionally, Bettas are often sold inexpensively in pet stores, which increases their appeal to hobbyists.

While Goldfish, Guppy fish, and Tetra fish are also common choices for freshwater aquariums, the appeal of the Betta fish, particularly its striking appearance and ease of care, distinguishes it in the context of this question. Betta fish are known to exhibit territorial behavior, especially males, but their ability to adapt to various water conditions and captivating personality add to their popularity in aquarium settings.