Fathom Incher
Quest reward from Return to the Sea. In the depths of the Endless Sea, strange thalassic horrors lurk. Not this fella, though. He's completely normal. Aquatic type. While you're adventuring in you'll probably kill creatures at the Sunless Strand and find a which will start .
The 
Fathom Incher is a battle pet reward from the quest Return to the Sea, obtained through a quest chain that begins with a dropped item in Hallowfall.
Guide awaiting review
Loot the Gasping Fish
While killing creatures at the Sunless Strand in Hallowfall, loot the 
Gasping Fish, which automatically starts the quest Gasping Plea.
Find the Peculiar Fish
Follow your map to the Peculiar Fish at 54.52, 25.33 in Hallowfall to begin the Crushing Depths quest chain.
Complete the Quest Chain
Work through the Crushing Depths storyline, which includes the quests Tidal Charms, Voices from the Deep, and Alluring Offer, ultimately leading to Return to the Sea.
Dismount Before Throwing
When reaching the step that requires throwing the fish into the water, dismount completely — the extra action button for Put Me in the Water will not appear while mounted.
