With two million admissions a year and 159 corporate donors, there's no question of staying afloat.
Yet aquarium officials have come to Washington with their hands out, seeking taxpayer-funded earmarks, grants of money without the normal public review, CBS News investigative correspondent Sharyl Attkisson reports.
And the Aquarium has found friends among at least six of their home state members of Congress, including Sen. Barack Obama.
They each received campaign donations from Aquarium officials, and then colectively channeled nearly $1.8 million in earmarks to the Shedd Aquarium for this year, after first receiving campaign donations from Aquarium officials. Both sides say the donations have nothing to do with the earmarks.
"The insinuation that somehow I got a contribution, that's what led to this, is nutty - to be direct," said Rep. Rahm Emanuel, D-Ill.
Emanuel says he supports the Aquarium because it raises awareness about the Great Lakes.
But the Aquarium does lots of other things with the money it makes. It spends some of it on Washington lobbyists to get the earmarks: more than $270,000 dollars.
It spends a healthy chunk of money on fancy fundraising parties, more than $600,000 worth in 2006.
And the non-profit Aquarium is also generous with its executives. The head of the Aquarium got a $60,000 raise in 2006. That's more than most people make all year.
His salary and benefits total over $600,000.
Even with all those costs, the Shedd Aquarium takes in much more than it spends through ticket sales, donations, souvenirs and more. Last year they cleared $8 million after expenses - and they're sitting on hundreds of millions of dollars in net assets.
All of that was enough to make a tax watchdog group classify earmarks for the Shedd Aquarium as pure "pork."
"The interesting thing about the Shedd Aquarium is that it's extremely wealthy," said Leslie Paige of Citizens Against Government Waste. "Why they need $1.8 million of taxpayers' money is beyond us. They don't."
"It's almost as if Congress is looking for an excuse to find somebody to give money too when they don't need it," Attkisson said.
"And I would guarantee ya those who know about it, and they do know about what I've done for Shedd Aquarium, support it," Emanuel said.
Which is why Emanuel has already announced his plan to earmark $2 million more to the Shedd Aquarium for next year. When fishing for tax dollars ... there's always a good catch in Washington.