Betta fish—also known as Siamese fighting fish ... wild bettas are smaller with shorter fins, and are a dull gray, green, olive, or brown. Before mating, the male spends hours blowing bubbles ...

These colorful patches appear with shimmering, iridescent scales. More expensive koi betta fish might have splashes of blue, green, pink, or purple. Koi betta fish tend to be aggressive and unfriendly ...