Wait, were there live fish in the original Submarine Voyage?!
There have never been live fish in the Submarine lagoon because of the highly chlorinated water (which also was notoriously tough on the hair and skin of the live mermaids that were part of the attraction in its early years).
"With the acquisition of Marvel and now of Lucasfilm,
Disney may have finally found the grail. You don't need
imagination or art. All you need is a brand."
- Neil Gabler
The footage with live sea creatures was solely to 'spice it up' for tv, and probably shot on the stage built for 20,000 Leagues at the Disney studio. Disney did the same when Pirates opened, 'enhancing' the attraction via television: the TV coverage shows the overhead barrels before the final lift hill literally exploding over the boat full of guests!