AWESOME! I look forward to playing this again! =)
Another small suggestion: you could drop the space/E buttons entirely and rely strictly on swarm placement/collision. For example, if I position the swarm over a weed, every fish that collides with the weed would "eat" the weed a bit more until the weed is removed. Same with hiding from predators - I would just need to move the swarm to the center of the anemone and they will hide in it as long as they are swimming within its borders.