I've never seen one on a toilet, but they are really common in the aquarium hobby. 

For example, "fish tanks" is a head term, but "compare prices whisper aquarium filters" is a long-tail keyword.Beginner search marketers often focus on head terms when optimizing their sites for organic search or creating pay-per-click campaigns.

It sucks.Ouch, and you can't even get a small load of sapphire to put into the aquarium.

I had one person who had sea turtles in a 40 gallong aquarium.

Check for other moisture producing items, like plants, aquariums, water fountains, etc.

We don't charge extra for them but I also make sure to advise them to get renters insurance-just in case (think aquarium leak)

There was AQUARIUM GRAVEL inside the drain pipe!

Aquariums greater than 12 gallons must be completely insured.

No aquariums without approval. $10 per fish.

I was much more concerned with the 90 gallon aquarium they wanted to bring.