The Shedd Aquarium, has a hawksbill sea turtle that was injured by a boat propeller. This affected her buoyancy, so it is not safe for her to live in the wild. She likes to play catch with her physical therapists. This species is critically endangered because of being over hunted for their shells. Since the 1970s there has been a worldwide ban on the tortoise shell trade; any "tortoise shell" items you may buy now are either dyed horn or plastic.
Clownfish cannot just live in any anemone. It's certain breeds for certain homes. You probably know that clownfish eat an anemones' left overs, but did you know anemones eat clownfish poop? Finding Nemo didn't cover that. Finding Nemo also didn't discuss how when the mother died, Marlin would have become female as he was the largest fish in their grouping. I can see how sequential hermaphroditism may be confusing in a children's movie.
Giant clams, native to the South China Sea, can weigh over 400 pounds! They are most often harvested for food. The shell of a giant clam is not lined with mother of pearl, so the pearls they produce are oddly shaped and matte in color, like a white walnut.
My husband called these "sea pencils," but they're actually pipefish, a relative of the seahorse. As with seahorses, attracting a mate involves lots of writhing and shimmying then BOOM!, the male wakes up pregnant and alone.
The porcupinefish has few predators for three reasons. One, its puffed up size makes it too big for the mouths of most fishes. (When they puff up, a porcupine fish has to swim upside down to maintain buoyancy.) Two, spines are ouch. Three, some of the internal organs are highly toxic, which you know if you've ever seen an episode of a crime show wherein the fugu did it.
Speaking of fish that hurt, round stingrays live in the Pacific coastal waters of North America. So wear water shoes if you're hanging out in those waters because the stingray sting is painful! They don't want to hurt humans; they just don't like being stepped on. If you are just near one, it won't attack. Stingrays actually shed and replace their tails every fall.
The mandarinfish (pictured) is not to be confused with the distantly related mandarin fish. He's small, slow, and pretty freaking majestic. Look at him. He's going to out fabulous all the other fishies out there.
The Coral Reef Alliance has more information about coral reefs and their conservation. Without the reefs, these animals wouldn't have anywhere to live, eat, and breed.