Bright fish are a group of colorful, freshwater fish that are popular in aquariums. The term includes tetras, which are small, schooling fish with bright colors and patterns; neons, which are small, slender fish with bright stripes; opahs, which are large, flat fish with bright spots; and tetras, which are larger versions of the tetra. All of these fish are known for their vibrant colors and active behavior, making them a popular choice for aquariums.