Name of the bias where someone really needs something after they find out it exists I'm looking for the name of the cognitive bias that is expressed in the following story.

A fellow coworker was instrumental in getting a 75 gallon fish tank installed in the lobby of the company that we work at a couple of weeks ago. The water needs to cycle for a while before fish can be introduced. The other day he was testing the water when someone walked by and asked when we would be getting fish. He said probably a week or so. The person was appalled that it would take so long to get fish.

The company had been without a fish tank for 20 years and now they've had one for a couple weeks and this person thought one or two more weeks was way too long to wait. What is the name of this bias?
It's not a bias. It is natural human nature. At least the 2 year old's case is.

It's just like how you would not have thought of going to Six Flags (An amusement park) unless it was mentioned to you. 

When the 2 year old hears ice cream, the kid thinks of the sweet taste, or the pleasure ice cream brings. In the kid's case, the case is impatience or inability to defer gratification. 

For the employee, it is simply that he thinks the cycling of the tank and fish delivery would take less longer than a week or two.

The two examples are both different things. I am positive that the 2 year old's case is NOT a bias. The employee's case may simply be surprise.