If you have raccoons, those fish are NOT safe in that container. I've known them to open cabinet doors, dump over heavy containers, to get to food. I don't think they can dump your container full of water, but I would not put it past them. Put some type of screen over the container at night, if possible, and secure it tightly. Don't just lay a screen on top, as the raccoon will simply move it! Yes, they are very clever, and your tub pond is shallow enough I'd guess they will grab the fish in short order, and if not, stress them enough to cause them to die. Protect them if you can.
But, also keep this fact in mind when building your larger pond. If the sides are straight down, the raccoon will not be able to "go fishing". Yes, I know your tub has straight sides, and the depth might be deep enough, but I kind of doubt it. So, straight walls, except for an area with steps dug into the edge so you can safely go into and out of the pond after it's full. Just remember to have a hiding spot in the deep part for the fish, if predators come calling.