As shown in "Imperfect Harmony", this Nadder was lured by the Death Song's melody and trapped in its amber. When the gang arrived, Toothless attempted to break it out by biting the amber but failed to do so. Though there was no mention of it escaping, it is presumed that the gang freed it along with their own dragons and the other victims.
In the series, this dragon is cyan with purple and pink hints on the edges of its wings and around its eyes
In Rise of Berk, however, this dragon is purple with pink rings and yellow spikes. Its chest is encased with the Death Song's amber.