Long, flowing fins and brilliant colors combined with easy care make betta fish a popular choice with novice aquarists. While your betta's coloring won't peak until he is 6 to 8 months old, and will fade naturally with age when he reaches about 3 years, your fish may become pale and faded for a number of reasons when he is still in the prime of life.
Check the Water
Although betta fish don't need a fancy aquarium setup, small vases and jars become toxic with ammonia within a couple of days. High ammonia levels stress the betta, causing him to become pale. Your betta will let his colors shine when he is in a healthy, comfortable environment. His tank should be a minimum of 5 gallons and heated to between 78 and 82 degrees. Filtration and plants remove toxins from the water, which can make his colors fade by making him feel ill.
Let Them Eat Shrimp
If bringing your betta's environment to ideal conditions doesn't brighten his color, enhance it with natural foods containing carotenoids. The pigments naturally found in brine shrimp and other crustaceans can be purchased from the fish store, labeled as color-enhancing foods. If your betta is consuming a diet of mostly fish food, he may become constipated and his color pale. Feed him a mashed, cooked pea to help things along and he'll return to a bright color.