Unity Fish Swimming Animation

I already have a layered PSD of my fish and a short reference video showing the style and timing I like. What I now need is a reusable animation clip for Unity that makes the fish feel alive in-game.

Here’s the behaviour I’m after: the fish should swim with noticeable acceleration when it starts moving, glide at cruising speed, then decelerate smoothly before it changes direction. Rather than following a fixed track, it must wander freely inside user-defined X-Y (or X-Z) bounds, picking a fresh heading each time it slows down. No collision or flocking logic is required—this clip is purely about natural movement, not environmental interaction.

Please create the animation (and any lightweight C# helper script, if you prefer that over pure Animator curves) so I can drop it straight into Unity 2021+ without extra setup.

Deliverables:
• Unity package or .unitypackage containing the animation clip, any controller / script you used, and the imported prefab using my PSD sprite.
• A brief note or read-me explaining how to change the boundary size or speed values.

If the fish glides convincingly with that accelerate-cruise-decelerate rhythm and roams randomly inside the limits, I’ll consider the job complete.