If the question is, can you add essential oils to your fish tank? The answer is YES. But if the question is, should you add essential oils to your fish tank? Then the answer is NO, as there are too many variables to consider, and the dangers far outweigh any potential benefits. However, not all fishkeepers will agree with that statement, and this is where the confusion begins for many people. So let's take a closer look at essential oils, what they are, and what they do. I will follow that by examining the pros and cons of adding essential oils to your fish tank.