Here is my guide to getting your cutie Glimr murloc pet. I recommend doing this on a druid, so you can use fast travel form for quicker movements in water or at least have our water mount at the ready. Bringing along a Warlock for water breathing might be helpful as well. You can also use things like your legendary fishing pole or mechagon Pocket-Sized Punch card with swim speed added to it. None of these are needed to complete this but it will make it a lot less difficult to complete since you will be fighting against Fatigue timers trying to get the things you need for this.
Start in Northrend go to the iceburg in grizzly hills @(18.4, 88.4). Every 5 min. a quest will spawn off a murloc called Glimmerfin Scout. He will run away and a quest called "Glimmerfin Scale" will be left on a scale here.
You will receive needed water breathing potions for the next quests to come. Much needed potions if you're not a warlock or a druid.
This will send you across Northred to To King Mrgl Mrgl in Borean Tundra of Winterfin Retreat. You can bring a mage buddy, to go to Dalaran and only take half the trip.
The king will tell you where the scale came from so you can go welcome them by offering them crab meat to gather with "Glimmerfin Welcome." He will also attach a cutie to you like this one with a little squid on its head, awwwwwww.
The meat is south of ventura bay in Grizzly hills. Glimmergut the leader will be in a ship deep below the water once you have all your meats. Luckily you have your water breathing elixirs and/or swim speeds to help you.
Now that you have pleased Glimmergut he will ask you to go to Kill Horker in "A Big Horkin' Task," for his blubber.
Blubber in hand, you head back and are sent over to Glimmerfin Oracle with "Seer of the Waves," who is at the very bottom of the ship so go through the back door and down below.
Now this is where all your water extras come into play. You will be sent to do "Giant Pearl." You need to get a giant pearl from under a Giant Water Serpent Elite Called Gem-Eyes. If you go to far off the edge of his area you will quickly gain Fatigue. Since you can't swim very fast it will take longer to get in and out of it and you could die from drowning or fatigue. So get down, kill and grab the pearl as fast as you can without hitting the Fatigue if you can.
After you bring the oracle the pearl you are asked to battle Trainer Grrglin In Trainers Test.
I took a few friends did many diffrent combos on all of us and really any strong level 25 pets will be good. I recommend Nexus Whelplings though since they seemed to rip all of them apart. I used a Emperor crab Nexus Whelplings, and Amberglow Stinger to get it done. But they are not very strong and any strong strat will most likely get the job done.
Now that you defeated him pick up, "Wrap it up." Where the ultimate Fatigue boss comes to play. I recommend using the cliff as a safe spot going down for one seaweed. Standing back on the cliff in the water till your fatigue bar goes away and again for the other two. The cast on water mounting just isn't a fast enough contender.
I died to the Fatigue boss and had to use another water breath potion till I did this. Mirma on her druid had less of a hassle. She got two, went back up then got the last one.
Your last quest will be Gaurdian of the Smallest. You need to Kill Great Mau'kin as your last test. Once you kill him they reward you with your very own Glimr!!!!
Glimr battles with Punch/Water Jet, Lucky Dance/Egg Barrage, and Ray of Hope/Whirlpool at 25 but he starts at level one. He is already Blue quality so you wont need a rare stone. Congrats. Let me know if this guide helped you! Special Thanks to Mirma Phor Dizzy and Nic for the company.