A koi's color cells sit at different depths in the skin, some right near the surface and some deeper in, which ultimately determines how bright the fish appears. The brighter the fish, the bigger ...

The color of the koi has meaning in Chinese mythology, too. Black koi absorb negativity, according to Novy. Yellow fish are about money and prosperity. The orange and white fish, which are the most ...

For example, stress can temporarily make your betta fish look duller. Luckily, you can restore their colors by providing a well-maintained aquarium and a proper diet. Koi fish, like most fish on ...