I know from giant fish, but this thing is a MONSTER.

It might be the world's largest freshwater fish.

http://pandawhale.com/post/59963/car-size-stingray-may-be-worlds-largest-freshwater-fish

Oceanic Manta Rays reach almost 3,000 lbs!

http://en.m.wikipedia.org/wiki/Manta_ray

But that's not freshwater.

What eats a ton and a half of manta rays? Is it whales or is it schools of smaller fish?

Killer whales and sharks ...cookie cutter sharks!

Mantas get the oceanic equivalent of a mani pedi:

Mantas visit cleaning stations on coral reefs for the removal of external parasites. The ray adopts a near-stationary position close to the coral surface for several minutes while the cleaner fish consume the attached organisms. Such visits most frequently occur when the tide is high.[36] In Hawaii, wrasses provide the cleaning; some species feed around the manta's mouth and gill slits while others address the rest of the body surface.[21] In Mozambique, sergeant major fish clean the mouth while butterflyfishes concentrate on bite wounds.[33]:160 M. alfredi visits cleaning stations more often than M. birostris.[33]:233 Individual mantas may revisit the same cleaning station or feeding area repeatedly[37] and appear to have cognitive maps of their environment.[22]

Coral mani pedi sounds like fun!

It's your dream to just float somewhere and have little fish groom you, huh?

Yes! Yes! That is my dream!!