I discovered the strangest thing while performing routine maintenance on my aquarium today. I have two light fixtures, one of which is situated on top of the rim of the tank just a couple of inches above the water with no cover between. In order to do water changes, etc, I have to remove that fixture. I usually use that opportunity to dry any moisture that may have accumulated on the light due to condensation or splashing. Well, today I found what looked and smelled a lot like urine drying (burning) on the bulb! I have no other pets, so there is no chance that a cat walked by and sprayed the last time I did maintenance. Is it possible that a fish could have been "relieving" himself at the very moment that he broke the surface of the water for some reason and peed on my bulb???