Archeologists say that birds have been found extensively in strata.  They were here in the dinosauric ages before the destruction that caused the  earth to be dark, formless, and void—birds didn’t come out of the water millions of years later during the period we are calling the Gap.  
And we know that most fish species never went extinct. They date back before the dinosauric destruction by millions of years.  Fish never vanished.  They never changed much within the species.  Some species that are still here and look almost exactly like they always did.  They didn't evolve. 

Which means that birds and fish aren’t connected, because they were both independent of each other; both were living on earth before the end of the dinosaurs. They weren’t connected then.  They aren’t connected now. They are different species.  The Bible isn’t saying they are connected.

I believe the verse is actually saying two different things.  “Let the fish…” multiply (bring forth) abundantly. And “…let the fowl…fly above the earth.”  And reproduce and diversify.
A shark from millions of years ago is easily identified as a shark.  Fish remained in the oceans and seas and reproduced in like kind through the ages.  Evolution theorists say that some worm had to evolve (and get a spine so creatures could stand up) so they eventually developed a "notochord."  They point to a creature called the amphioxus as the transitional stage.  However, the amphioxus exists today.  It hasn't changed or evolved.