Help! I'm A Fish - Plot

Plot

The film follows the adventures of three children: a skateboarding mischief-maker named Fly; his sweet younger sister, Stella; and their cousin, a cautious, intelligent and overweight genetics prodigy named Chuck. When their babysitter, Aunt Anna, falls asleep, the three children sneak off to go fishing only to stumble across the boathouse home of Professor MacKrill, an eccentric marine biologist. Reasoning that climate change will melt the polar icecaps within the next century, MacKrill has developed a potion that turns people into fish so they can survive the rising sea level and also an antidote to reverse the process. Unbeknownst to all, Stella drinks the potion, is transformed into a starfish and gets tossed out of the window into the sea. Since Stella's transformation was caught on camera, the tragedy is immediately discovered, so Fly, Chuck and Professor MacKrill head out onto the ocean in a desperate search. When a storm blows in, Fly recognizes the futility of their search, drinks the potion and jumps overboard, becoming a "Californian Flyfish". The boat capsizes and, because Chuck cannot swim, he's forced to drink the potion to survive, becoming a jellyfish. The Professor, the boat and all of its contents sinks beneath the waves.

A great white shark and a pilot fish come across the leaking bottle of antidote and gain the human characteristics of speech by inhaling the liquid. Using his newfound gifts, the pilot fish, who now calls himself Joe, sets about creating an underwater civilization of intelligent fish. They take residence in a sunken oil tanker and begin to transform it into a monument.

Fly, Chuck and Stella are reunited, along with a seahorse named Sasha, but are horrified to discover that the antidote has been lost. If they don't find it before tomorrow's sunset, they will stay fish forever. Some traveling fish tell them about Joe and his "magical potion". Thinking it must be the antidote they are looking for, the children travel to Joe's oil tanker empire.

At the tanker, Fly attempts to steal and drink the bottle of antidote, but is warned by Chuck that if they turn back into humans this far beneath the ocean, they'll die. Intrigued by this, Joe has the children arrested and demands they manufacture more of the antidote or he'll have them eaten by the Shark.

Meanwhile, Fly and Stella's parents, Lisa and Bill, arrive home to find Aunt Anna frantic with worry. They find that Fly's fishing equipment is gone, so they head to the beach to search. There, they meet Professor MacKrill who, having survived the storm, explains that their children have been turned into fish. Though the parents are skeptical at first, a showing of the video recording from earlier validates his story. He and Bill head out to search for the children in a cobbled-together ship fitted with a large water pump.

The next morning, the children manage to escape with the help of Sasha. With no chance of going back to retrieve the bottle of antidote, they decide that their best hope is to find the ingredients to recreate the antidote themselves. Just as they complete the formula, they are found by Joe, the Shark and their army of crabs. During the standoff, Joe and the Shark get into a heated argument. Taking this opportunity to escape, the children are stopped by the leader of the crabs who attacks Fly, then drinks the antidote himself. Just as the new "King Crab" and his army is about to capture the children yet again, a tremendous underwater twister, generated by the Professor's water pump ship, sucks all the crabs (and the shark) to the surface.

Now alone, with Fly dying, and only twelve minutes until sundown, Chuck realizes their last hope is to make it back to the Professor's lab, where a whole jug of antidote is stored. Showing unexpected courage and determination, Chuck carries both Fly and Stella through the dangerous seawater intake pipes back to the lab. However, they are pursued by Joe, who overpowers them and steals the antidote. While Chuck fights off the Professor's escaped piranhas, Fly manages to catch up to the fleeing Joe and tricks him into drinking enough antidote to become mostly human. Since Joe can no longer breathe underwater, he drowns.

Fly drags the jug of antidote back to the lab and collapses. Chuck uncorks the jug just as Lisa and Aunt Anna open the door to the laboratory, causing everyone to get swept away. As the water drains away, Chuck and Stella have become human once more and are reunited with their parents. After a few tense moments in which a stuffed fish is mistaken for the limp body of Fly, the human Fly emerges from one of the lab's pipes (with a broken leg). Later on, while playing by the beach, Stella is reunited with Sasha, who is turned into an actual horse by the Professor and Chuck.