Sad News from the Calgary Zoo

[i have crabs]

im guessing a possible disolved oxygen issue but just a guess, i would think if it was polluted by someone either by accident or on purpose it would have to be alot of something to mess up a tank that size and i just dont see it happening.
also trimming the stingers is the same as trimming your fingernails but im not shure how you hold down a 2' ray and trim its barb? and im quite shure the baby hippo did not die it was on loan from a zoo in quebec and is now back thier in a brand new exzibit.