Yellow Guppy Male. The yellow guppy will always have a yellow tail. This may range from the palest to the deepest, almost orange, yellow color. However, the body coloring may vary depending on the tail style. Yellow coloration appears on the gills and fins, but this color can appear in many other places as well; yellow splashes are seen on the fish’s face when it opens its mouth to eat a piece of food. Another characteristic feature these fishes have is extra flaps that catch more sunlight than if those parts were barely allowing them better access to what little light there is. If you decide to get one for your tank, these fish are known for being very active swimmers that love bright lights and have an aggressive temperament so do not house them together unless you want your guppy in trouble! They like doing well on any type of food, whether it is fruits or pellets.