Well folks the Harpoon of the depths drops off these guys....really easy to kill with about 1400-1500 hp's each. make sure to bring plenty of fish scales. as you will find yourself sitting here along time since at 50, they still con Blue and i get about a full bubble of experience every 2-3 hours.....BTW the stats on the Harpoon are +2 dex, +20 HP, war, pal, ranger, rogue, shaman, shadowknight, and bard.....check it out....
Sorry, but i think you have them mixed up. The bloodgill goblins drop the harpoon, very very rarely. this is a single spawn different and harder than the normal gobs. im not sure on how his spawn is, timed or has a PH, but he isnt up that often.
This mob is in the middle of the water, near the left most piller, follow the wall around and he is located between a iksar statue with 2 bloodgills next to him on each side. so Him and 2 other mobs you have to kill. I solo'd him at 49 but my pet killed him in the water and it took me 10 mins to kite him.