The translation goes "not every amphibian is healthy", but I guess it's wrong, I think it's "the situation is not good especially in terms of the healthyness of the environment" Am I right?
And additionally, if you happen to know why frogs are regarded as ecosystem's canary, please let me know.

ex)Frogs and other amphibians are good indicators of environment change for two reasons. First, they live in water and on land, and disturbances to either of these habitats can affect their health and abundance. Second, frogs live in almost constant contact with the environment......The eggs, too, are generally delicate and unprotected and therefore vulnerable to contaminants and environmental disturbance. Many biologists regard frogs as an ecosystem's canary in a mine; when amphibians begin to disappear, it is a clear warning that all is not well in their environment.