[Keri]

Originally Posted by digital-audiophile

So is it one of the maintenance guys in Calgary? I don't think the zoo would name names.

summary:

"The answer is 99.9% sure, we believe the dissolved oxygen was too low -- the life-support system was not designed to provide enough dissolved oxygen," said Lanthier.

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"We didn't have any expertise in aquarium and fish, so we partnered with a reputable designer of life-support systems, one that came with a recommendation, and that's what we implemented," said Lanthier.

While the system seemed fine for the first few months, Lanthier said the oxygen wasn't keeping up -- and when staff tried to save the rays, they altered the evidence.

Keepers rushed to move the rays to another tank when the first signs of distress were noted, and in disturbing the water, they mixed in enough oxygen to make tests useless.