The biggest fish in the ocean is the Rhincodon typus or whale shark. Despite their tremendous size and intimidating appearance, whale sharks are commonly docile and approachable. Please keep your distance, giving them the respect and space they deserve. Whale sharks can grow to 12.2 meters and weigh as much as 40 tons by some estimates! The largest reported whale shark was 20 meters, but it is uncommon to see them longer than 12 meters.