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When a outbreak of Eel Pox comes to Berk in "The Eel Effect", Hiccup and Toothless go to Eel island to retrieve the final ingredient for the cure; a bloodvein eel. However, when Hiccup falls into one of the eel-infested streams, Toothless leaps in and rescued him by biting in two the eel that was attacking his rider, unintentionally swallowing the head half. Following that, Toothless starts to experience the symptoms of eel pox himself and, unable to help himself, attacks Hiccup. When Fishlegs and Meatlug arrive to fetch Hiccup, they find out that the Island is also home to wild Typhoomerangs due to them being the only dragon that eat eels. While Fishlegs and Meatlug distract a Typhoomerang, Hiccup manages to capture Toothless, mix together the ingredients for the medication, and cure him before they finally return to Berk with the remaining ingredients to heal the ill Berkians.