The High Test Eternium Fishing Line is an enchanted fishing line that will add +5 fishing to a fishing pole. This effect will not stack with other enchantments on the item.
The High Test Eternium Fishing Line is a quest reward from the quest N  , which starts at the Neutral in Booty Bay in Stranglethorn Vale. To complete the quest, you must turn the following item to the Neutral :
A bug results in it sometimes displaying as "+2 Fishing Skill" when placed on the rod.