The fish will love your light no matter which color you choose! It is mostly a matter of personal preference, although the water clarity and type can affect the appearance of the bulbs in the water. For clear salt water, our colors will shine true, in brackish water, the colors will distort due to the particles the light shines through. Green bulbs will shine green in brackish water, but the blue light will shine with a yellow / orange light. Our red bulbs have been designed particularly for brackish water, as they permeate through the particles further than any other color we have tested. They will show as an orangish color, but if the quantity of light is important to you, the red bulb will give you the largest diameter of light in brackish water.