Bass fish swimming and taking the bait (lure) and get reeled in

I'm making synchronized flash ads and can do all programming for that...what I need is to animate a bass underwater, getting closer to the lure...then taking the lure in its mouth... then a synchronized ad reels the fish in. I've seen a basic bass fish asset for $15 on the marketplace I'm hoping can be used. I just suck with Unity and need help. If this would make a massive filesize then the project probably can't work, but hopefully I can find someone who knows how to keep file sizes low by 'faking' some things.