Fat Sleeper

No Need to fly around each day fishing for these guys. If you keep a stock of them; whether a few stacks of: 5 Enormous, 10 Regular, or 20 Small; as long as you filet them during the daily you will get the eggs dropped from them.
This leads to the next plus, if you purchase the fish in the AH or get some as a gift from a friend or guildmate, you will get the eggs from fileting them too. As long as you have the type of fish for your daily and filet it during the daily you will be able to complete your quest.
If you are working on Draenor Angler don’t just filet them all; hold on to them for your dailies.

I found the [object=229068] in "Skysong Lake" . The first 20 Small Fat Sleeper gave me 5 [item=112631]. Second one gave me 10. You will fish Fat Sleeper but those gave me only flesh.

To add to what Medracer said, you also don't even need to go to Nagrand to complete this. As long as you have the appropriate bait, you can fish these up at your Garrison Fishing Shack. Just apply the bait and fish, once you have the appropriate stack size depending on the size of fish you catch, filet them and you'll receive the item. This works for all the dailies at the Fishing Shack. Make sure you've accepted the quest prior to using the stack or you will not receive the quest item!