If perception is merely the processing of experience, then it seems likely that fish too have a consciousness, even if what they experience is dramatically different from what we perceive. It is possible to conceive of such a difference, even if it cannot be directly perceived: we know that the colour blind see things differently from us, even if we cannot see in the way they see. The differences are evident in our actions.
The consciousness can observe itself, but only through the sense it has been given, and thus the mechanisms behind consciousness can never be experienced, as such would require consciousness to already exist. The biological roots of experience are thus never known in full, and here we lose sight of the chain of causality between events and our actions.