For example, tell me:
* What is the commercial about? (e.g., a specific product, a holiday, a general theme)
* When did you see it? (e.g., recently, a few months ago)
* What is the aquarium like? (e.g., a giant tank, a small one, a specific kind of fish)
The more information you provide, the better I can help you identify the aquarium you are looking for.