Goldfish implosion
I worked in pet stores for 7 years, so I have a million of these stories.

A lady and her husband and children would come into the shop every Sunday after church with a large ice cooler and ask for 100 live goldfish to go in the cooler. I just assumed she had a pond with a bunch of turtles that ate goldfish, and never asked any questions. She was very talkative, and one day told me what the goldfish were for. She believed that animals should all be free and it was morally wrong to keep them in cages and fishtanks, so they would buy 100 goldfish every Sunday and set them free in the ocean. IN THE OCEAN. I took her aside where her kids couldn't overhear and calmly explained to her what happens to goldfish if they are put into saltwater. She became very angry, refused to believe me, and insisted on buying them anyway. I refused to sell to her and explained to the other employees who (stifling laughter) also refused to sell to her. Her anger escalated. She talked to the owner, who apologized and sold her the goldfish.
(cnidaria0 Cnidaria, Fri 5 Sep 2008, 1:16, 5 replies)

Seriously
why are there people like this?

Still, bloody good tale to tell people!
(WillyNilly SillyBilly, Fri 5 Sep 2008, 1:29, closed)

What happens when you put a goldfish in the ocean?
Obviously they will feel poorly and die quite rapidly, but your title intrigues me...
(AlfishKK, Fri 5 Sep 2008, 3:10, closed)

Not exactly implosion
If you put a saltwater fish or invertebrate into freshwater, they usually swell up and sort of explode. Put a freshwater fish into salt water and it dehydrates, which is a bit less spectacular than implosion. Basically freshwater fish in normal water have a hard time keeping up the salt concentration of their bodies, so they have certain metabolic processes to cope. Saltwater fish have a hard time keeping salt OUT of their bodies, so they pee (through their gills) concentrated saltwater.
(cnidaria0 Cnidaria, Fri 5 Sep 2008, 6:57, closed)

goldfish
Yeah, I got one of those, some bloody hippy wanted to feed their goldfish a vegan diet. I told her not to impose her lifestyle on something that can't make its own decisions.
(kilt101, Fri 5 Sep 2008, 19:54, closed)

Vegan predators
I would get a bunch of people asking for vegan dog and cat foods. They actually do exist, but I worry about the long-term health problems. Next people will try to get dolphins to stop eating fish.
(cnidaria0 Cnidaria, Sat 6 Sep 2008, 19:35, closed)