How long do seahorses live?

They can live about 3-5 years.

If you feed it properly it could live 1-7.

Where do seahorses live?

Seahorses can live in tropical and subtropical coastal and reef
waters all over the Pacific, Atlantic, and Indian oceans.

Seahorses live in saltwater and like shallow
waters.
You can find them in shallow waters, sea grass, and
coral. 

What do they eat?

Seahorses like to eat small shrimp and
plankton.

They also eat tiny fish.

Or small crustaceans floating in the water.

References

http://wiki.answers.com/Q/Where_do_sea_horses_live