The team must transform a Volkswagen Minibus into a fish tank for a local car dealer. Engineering a tank that will weigh 4,000 pounds when filled with saltwater and fish is the hardest task they have attempted so far. Meanwhile, fish geek Francis is looking for an assistant. Soon, he puts potential candidate Heather to the test by giving her a quiz on fish species, having her go on a deep-sea dive and having her perform a risky surgical procedure on a venomous fish. Will she make it?