There was a Cousteau show about sharks in the Pacific last night on PBS. Many shots of numerous sharks swimming lazily among dense schools of fish without taking a bite, and this was in the wild.
My guess is that sharks won’t eat if they’re not hungry, and even if they are, not all live prey is that easy to catch. So keep 'em fed and teach the small fry defensive tactics.
From my limited diving experience, groupers are carnivores, big, hungry and generally mean to the rest of the population.
(First post here; please be gentle if I screw up.)
Near where I live is a massive aquarium which contains some sharks swimming freely among the littler 'uns.
The OP’s question is a FAQ from the visitors to that place, and the stock answer is that they feed the sharks enough so that they’re never particularly hungry. Furthermore, they claimed - last I heard - that they’ve never knowingly lost a single fish due to shark attacks. I don’t know what their recycling policy is for dead or terminally-ill fish, though …
yeah well, you screwed up. Get lost. 
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Smiley aside, that remark was totally uncalled for, Sapo.
And please don’t say my humor meter is broken.
Chill out. That’s a strong suggestion.
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Welcome to the Straight Dope Message Board. 
My brothers and sisters on the Inside tell me that Sharks are not a problem as long as there are enough Jets around for them to squabble with. The only danger is that the fish will break into a huge dance number backed by an orchestra of trumpetfish.
Ever heard of a Super BassOmatic?
Barrington, don’t mind Sapo. He may be temporarily operating in gaseous mode.
By coincidence, I visited the Seattle Aquarium yesterday.
In their big underwater dome, we saw one big ugly bastard, like a sculpin but huge, enjoying one of his tankmates as a snack. He was swimming slowly, the tail of a smaller fish sticking out of his mouth, munching lazily away.
Also, in one of the “touch the tidepool critter” exhibits, the guide/staffer person mentioned that the tank with the starfish is kept separate from the tank with the oysters because otherwise the former would basically denude the latter’s area in less than a day. And even so, sometimes a starfish will clamber over the dividing barrier and chow down on a fair number of the mollusks before anyone notices.
Nature: red in tooth, claw, and fin, apparently.
I used to work at the Shedd Aquarium in Chicago (on the visitor services staff, not as a fishkeeper). They have a large coral reef tank that contains many types of tropical fish and a half dozen or so nurse sharks. Nurse sharks are normally pretty docile, and like to just sit on the floor of the tank. They are one of the few species of sharks that can pass water over their gills without having to swim constantly.
Anyway, the whole tank was kept well-fed and shark attacks were unusual, but they occurred. I remember specifically one evening the aquarium had been rented for a private party with dinner tables set up around the tank. One large fish was apparently in distress; it was swimming erratically and listing to one side. Before it could be retrieved and removed to an isolated tank, it was attacked by several sharks and literally torn to pieces in front of the whole dinner party
Dinner and a show!
Barrington, I hope that, Rico’s post to the contrary, it was clear that I was just making a joke taking advantage of the opening you kindly provided. No foul intended. Apparently it wasn’t obvious enough. Accept my sincerest apologies if any were needed.
I don’t think you could really describe starfish as being able to “clamber”; “crawl extremely slowly”, maybe. Or maybe they have ninja starfish.
Don’t worry, Sapo - I took it in the intended spirit.
:humbled:
figured. Welcome in (said the guy who hasn’t yet joined lol)
And, uh, how does one teach tiny fish defensive tactics, pray?
And welcome, Barrington!
And sometimes pale slimy grey, or whatever color mollusks are.
I once saw someone dissect a shark (small one in a science class) and most things in the stomach were whole. So I’d bet that you mostly don’t see sharks chewing or tearing apart, just making one quick dart and swallow, and farewell, goodbye, little fish.
Then they wipe their shark lips and smile, I just know it.
Boo! Boooo!!
The worst part is, I actually laughed. I’ll get you for this.
That’s right, pray. Not prey.
You use little chalkboards with teeny pointers wielded by tiny, tiny teachers named Mrs. Falbo…
Bravo! claps
I’d always heard that the reason the sharks don’t eat the little fish is because it isn’t efficient for them to do so. Basically, they would burn more calories in chasing and devouring the little fish then they would get from digesting them - sort of like humans eating celery. This is also why those aforementioned smaller fish like to school around sharks - because the kinds of fish who would make a meal out of them are big enough for the sharks to eat.
