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Steinberg: Shedd fish offer food for thought

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Updated: April 4, 2013 6:04AM

Fish eat fruit. And vegetables. Some do anyway. Lungfish nibble lettuce. Stingrays eat their peas, though floating peas will clog a tank’s filter if you’re not careful. The Shedd Aquarium goes through about 4 tons of fruit and vegetables a year.

Aquatic creatures have a range of surprising eating habits — some turtles like bananas. If you asked which eats more, an 80-pound sea otter or a 2,000-pound whale, most people would probably guess the whale — much bigger — and they would be wrong. It’s the otter. Otters have no blubber, and thus must consume a quarter of their body weight every day to stay alive.

When you think of feeding fish, what do you imagine? Tapping a small canister of dried fly flakes over Goldie’s bowl? Just doing that can be enough of a challenge. What must it be like to feed the roughly 32,500 animals housed at the Shedd Aquarium? Seven days a week, 365 days a year?

How do they do that?

“Everything is compartmentalized,” said Michelle Sattler, the Shedd’s collections manager. “We have reptiles, birds, mammals, invertebrates, fish. We have everything.” (People might forget the Shedd’s birds: 20 penguins, plus two owls and two hawks).

Sattler’s particular responsibility is the Caribbean Reef, a 90,000-gallon tank housing hundreds of fish, from 60-pound stingrays to butterflyfish weighing a few ounces. Divers go into the reef to feed the fish, which I always thought was purely for show, but has a practical purpose — some fish are aggressive and territorial, and if aquarium personnel just dumped food into the top of the tank, as with goldfish, half of the fish would starve to death while the other half got fat.

Yes, fish can get fat. That’s why the Shedd keeps track of what many animals in its care eat, particularly larger species, and uses clickers to train some fish to eat on cue.

Piscine competitiveness makes hand-feeding less fun than it looks — it isn’t all floating around and answering tourists’ questions. Divers can get beaten up by hungry rays.

“The stingrays in the Caribbean Reef, they’re big and they’re strong and they can be bullyish,” said Sattler. “They weigh 60, 70 pounds and they can push you around, if they feel like they can get away with it.”

What else do fish eat? Just about everything. The Shedd uses 100,000 crickets a year. Plus tons of a seafood gel. Then there’s regular seafood — the Shedd buys a quarter million pounds of restaurant-grade seafood each year — shrimp, herring, squid, mullet, mackerel. The staff checks over every last smelt in the Shedd’s five kitchens.

“We have a crew that start at 5 a.m. We do a quality sort that usually takes four hours,” said Madelynn Hettiger, senior trainer, of the marine mammal department. “We look through every single fish, to check for missing eyeballs, to see there are no tears or breaks in the skin, no freezer burns” (important because bacteria that could harm the Shedd’s fish could settle in the cuts).

If you’ve ever grumbled about the admission price at the Shedd ­— and who hasn’t, with an adult pass being $28.95 ­— think of those ravenous sea otters.

“It costs more to feed five sea otters than all the animals in the oceanarium combined,” said Hettiger.

Increasingly over the past decade, the Shedd raises its own food for its animals.

“If we can grow our food here, we do,” said Mark Schick, manager of special exhibits. “There are several advantages ­— one, we know we always have it.” Which isn’t always the case when grub is jetted in. The Shedd has had some nervous moments in the past due to shipping snafus, suddenly out-of-business fisheries and the occasional gulf hurricane. It isn’t as if you can serve your sea lion a few TV dinners while waiting for FedEx to track down that shipment.

“If you want to get a cheeseburger, there are many places out there,” said Schick. “If you want mysid shrimp, there are very few places out there.”

Thus hidden from visitor view, in low spaces behind the tanks, is a burgeoning effort to raise food — water fleas, crayfish, rotifers — for the Shedd’s collection.

“It’s far less expensive to grow food here than to ship it priority overnight,” said Schick.

Living food is necessary, because some fish will eat only moving food and won’t touch prepared food. They also have to raise food to feed the food that feeds the fish. That explains the 24 bubbling gallon bottles of algae, the various shades of green denoting degrees of maturation. (The Shedd also makes its own sea water using — what else? — crates of Instant Ocean, “The World’s No. 1 Sea Salt.”)

One mainstay of the Shedd food program has an unexpected nostalgia connection — mysid shrimp — which have the benefit of being able to stay alive in suspended animation until needed and mixed with water, a talent developed in dry African lake beds, which gave them a passing fame under a different name in the back of comic books.

“Sea Monkeys,” said Schick. “Remember when you were a kid?” He feeds the quarter-inch-long brine shrimp — which, contrary to the comic illustration, do not have faces or hands, but look like tiny translucent grains of rice — to the Shedd’s sea horse and sea dragon collection.

“If we were buying them, it would be hundreds of dollars a week,” said Schick. “Raising them is a fraction of that.”

As with most people, fish crave variety in their diets.

“Salads are great for you, but you don’t want salad every day,” said Schick. “With fish, it’s the same way. We like to spice up their diet and enrich them with living moving targets.” Sometimes food is frozen into ice blocks, or tucked inside feeder balls, just to keep it interesting.

As much a routine as feeding fish at the Shedd is, as with human food, there is an aspect to feeding that transcends the physical. The staff, which sometimes names the fish under their care, develops attachments to certain fish and demonstrates those attachments through food.

“I have a fish that, for me, is very coveted,” said Sattler, who has been at the Shedd for 14 years. “It’s a beautiful little fish, When I took the exhibit over there was one individual of this specifies, I saw it, it was smaller, hanging out in the corner, I asked, ‘What is that fish?’ They said, ‘That’s a boga.’ It’s beautiful.”

She encouraged the Shedd to collect more bogas.

“I have a group of them, kind of like my babies,” she said. “Even though the exhibit gets fed four times a day, I like to go up to the top and sprinkle food for them.”

Because you love them?

“Yes,” she said. “Because I love them.”

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