you don't evolve from something that still exists...
That's exactly how evolution works. It's been observed in action.
Either there was a phenomenonal mutation (which wipes out the previous species) or an implementation of a new a species all together.
That's exactly the opposite of how evolution works.
Fish are still here..and if only some species of fish "evolved", why not all species of fish?
Back up. Explain why you think all fish would evolve into a new species at the same time?
More importantly, why was there a need to evolve? A message like the one presented provides no insight into this fundamental question. Darwin failed miserably at it. And I challenge any evolutionist to show proof of a NEED for humans to have evolved from any other species that lived on this planet.
To survive under changing environmental conditions, for one. But, in any event, populations change over time, regardless, that's a fact. It just IS. Need may not have anything to do with it.