Dareth and the kids are going to a field trip to Ninjago City Aquarium to see the Electrocobrai and the sharks while the Ninja are looking for the hard drive. The Stranger sneaks in and steals some Electrocobrai. Then, a shark escapes, but Dareth scares it away, using his knowledge of the language of the sea.
After the Ninja captured a Fangfish that was responsible for terrorizing a coastal village, they intended to send it the the Aquarium. It was placed in a tank and was presumably transported there.