Step 1: How to get the Mysterious Bottle

Once you arrive, make your way down to the beach by following the route to the Royal Terrace, past the pool and down to the beach. When you reach the bottom of the stone steps leading to the beach, look to your left, and you'll see the Mysterious Bottle item just past a palm tree, washed ashore by the waves.

Pick up the bottle and you'll gain a cryptic list of instructions, beginning the quest. Of course the Mermaids have to be secretive, so it's time to figure out how to contact them.

Step 2: How to fill the Mysterious Bottle

Now you have the Mysterious Bottle, we'll need to wait for it to be night. Unfortunately, there's no skipping ahead here. You have to pass time until the clock reaches around 7 o'clock, and the sun goes down.

Once it does, return to the beach, step into the water and fill the Mysterious Bottle with ocean water, creating the Bottle Of Bioluminescence.

Step 3: How to activate the Bottle Of Bioluminescence

Now we've got a full bottle of lovely glowing ocean water, take it up to your dorm room. You can easily get to the dorms by clicking the "Dorm" button on the tab to your right. Claim a dorm and head inside.

Once you're in, you'll need to go to your Decorate menu, tab to your inventory, then select the Bottle Of Bioluminescence and put it on the floor of your room. Now, head to the shopping tab and look for a candle. If you type “candle" in the search bar, you'll find a few options you can choose from. Buy three of whichever candle is cheapest, then plop them around the Bottle Of Bioluminescence on the floor.

Finally, turn the lights off, equip any elemental spell you have and cast it on the bottle. It's easy to think it's not working because the spell isn't hitting the bottle, so if it isn't triggering, stand over the bottle and aim directly down. You'll cue a cutscene, and after it, we'll move on to step 4.

Step 4: How to form the Fishling Egg

Once the ritual is done, place a bed in your room and buy a single pillow. Place the bottle on top of the bed, then the pillow in front of it. Now, wait until it's night again, then stand on the bed and lie down as close to the pillow as you can using the pose commands on the left-hand side of the screen. If you're in the right spot, the game will notify you that you're "protecting the bottle," meaning we're all good and things are progressing correctly. Hold fire from here.

When you reach morning, the bottle will teleport into your hands and glow red. There's now a big ol' fish egg in there! Congrats, you're a parent! You'll now be prompted here to name the fish egg inside, so give it a cool handle, like Wilbur. Wilbur's a great name.

Step 5: How to build a bond with your fish

Now that your egg is depending on you, you have to be a great fish parent and shove that little guy in your locker to teach him independence. Head to your locker and put the fish egg inside. From here, your task is to head to your classes, and in the time between lessons, return to interact with the egg by clicking on it with the mouse. Make sure you're doing it between every lesson in the day to maximise the fish's growth.

Eventually, you'll interact with the bottle, and you'll get a notification telling you that your fish has hatched.

Step 6: Free your fish

Unfortunately, fish don't belong in bottles. We need to release our new friend so it can be back among its people. Head down to the beach where we first found the bottle, and you'll get a prompt to release your fish. Hit it, and you'll watch a long cutscene that concludes with you getting a Mermaid tail. Your tail will change depending on your magical element, and your little fish friend will swim along with you, making this a pretty nifty reward.