Tank makes his first appearance in the Episode May the Best Pet Win!
Depiction in the series:Edit
He is introduced in the Episode May the Best Pet Win! He's actually named after Rainbow Dash had chosen him as her new pet. He was chosen over a handful of other pets.
Through the entire Episode, Fluttershy insistently correct to the others when they mistake Tank for a "turtle", instead of a "tortoise".
Rainbow Dash, her toy comes with a with a turtle that was presented at ASM's 2011 Toy Fair, and is later sold in retail. This episode is written at the same time, just about a year prior to the episode's airing.