Stardew Valley: How to Complete the Aquatic Overpopulation Quest



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Demetrius requires help maintaining balance in Stardew Valley’s marine ecosystem, so he puts up a request titled Aquatic Overpopulation. Here is all you need to know about Demetrius’ special order quest.

Stardew Valley: How to Complete the Aquatic Overpopulation Quest

Demetrius is a scientist who studies the valley’s wild creatures and their habitat. You could say he is a man purely dedicated to his work, seeing that he and Robin built their house in the mountains where he could easily access and observe the wilderness. Demetrius wants to do something about the rapid population increase of fish, and he will need your angling skills to thin out their numbers.

Quest Requirements

The quest can be accessed in the Special Orders Board. You may find that residents from Pelican Town like to pin up various requests and orders on this board in exchange for crafting recipes and money. As a bonus, you’re also rewarded with new cutscenes after finishing some of these quests.

The board is located south of the Mayor’s house and across the bridge to the beach. However, it can only be unlocked after Fall 2 in Year 1. Demetrius will indicate which fish you will need to catch, and you will be required to catch ten fish within seven days. It is recommended you accept the quest on a Monday should you encounter it, as the time limit will gradually shorten if you let the days of the week pass.

Apart from unlocking the Special Orders Board, there are no other requirements you will need for this particular quest.

Completing the Aquatic Overpopulation Quest

Regardless of how Demetrius describes his quest, some players think the ponds, oceans, and rivers are far from being overpopulated. Perhaps due to bad luck, some fish species are scarce and hard to catch. So if you feel like you haven’t had much luck catching the fish you need, you can refer to the tips we have for you below.

Fishing Strategies

The aim is to catch more fish than trash items. Fishing takes time, so knowing the proper strategies can bump up fishing efficiency. Due to certain circumstances, you may not be able to get a bountiful haul no matter how much time you spend fishing.

For instance, having a low fishing skill level means you will have a shorter casting distance. Most players already know that when you cast your rod, a meter pops out and fills up as you hold the action button. Once you let go of the action button, the fishing rod gets thrown into the waters. Some may not notice this right away, but your fishing rod’s line gets longer whenever you level up. Improving your fishing skills allows you to cast your rod at a greater distance. And you’re less likely to get trash when you throw your rod farther from the shore.

Having fishing experience will certainly be advantageous. But if you are not quite skilled in fishing, tackles like Dressed Spinners and Curiosity Lure can increase your chances of reeling in more fish than rubbish. Hooking up your rod with bait is also recommended to catch quality fish.

You can craft fishing tackles or buy them at Willy’s fish shop. Bait can also be purchased from the fish shop, but you can make bait using a Worm Bin. Worm Bins are quite costly to craft, but they can produce 2 to 5 pieces of bait every day.

Rations such as Seafoam Pudding can also temporarily boost your fishing skill level in a few in-game minutes. Whip up Seafoam Pudding with Qi Seasoning to enhance its quality and stat buffs.

Enchantments like Master can add an extra level to your fishing skill when equipped and Auto-Hook, as the name implies, automatically hooks a fish when it bites on your fishing rod. These abilities can be added to your fishing rod if you merge it with a Prismatic Shard at the Volcano Forge.

It also helps if you have good or great luck when you go fishing. The spirits’ mood can affect your daily luck, so tune in to the fortune teller channel daily to check if they feel happy, neutral, or annoyed. Pumpkin Soup, Spicy Eel, and Lucky Lunch are consumable items that can help increase your luck.

Fish Locations

After making the necessary preparations, you can finally start fishing out your mark. Fish in Stardew Valley can spawn in different locations, depending on the time of day and the season. Therefore, we have listed below where you will be able to locate all the fish Demetrius may request:



Found in the ocean at the Beach, Beach Farm, and Ginger Island West. (6:00 AM – 7:00 PM)


Caught in the ocean. (6:00 AM – 11:00 PM / 7:00 PM – 2:00 AM)

Largemouth Bass

Located in the Mountain Lake. (6:00 AM – 7:00 PM)


Obtained in the ocean. (6:00 AM – 7:00 PM)


Caught in the River only when it’s sunny. (6:00 AM – 7:00 PM)



Caught in the Forest river. (6:00 AM – 7:00 PM)

Rainbow Trout

Found in the river in Pelican Town and Cindersap Forest. (6:00 AM – 7:00 PM)

Red Mullet

Located in the ocean at Beach or Beach Farm. (6:00 AM – 7:00 PM)


Found in the ocean at the Beach, Beach Farm, and Ginger Island. (6:00 AM – 2:00 PM)


Caught in the ocean at the Beach, Beach Farm, and Ginger Island. (6:00 AM – 7:00 PM)



Reeled in from the ocean. (6:00 AM – 11:00 PM / 7:00 PM – 2:00 AM)

Midnight Carp

Caught in the Cindersap Forest pond or Mountain lake only at night. (10:00 PM – 2:00 AM)


Found in the Pelican Town or Cindersap Forest rivers. (6:00 AM – 7:00 PM)

Tiger Trout

Caught in the river at Pelican Town or Cindersap Forest. (6:00 AM – 7:00 PM)



Obtained by fishing in the Pelican Town or Cindersap Forest rivers. (6:00 AM – 2:00 AM)


Caught in the river at Pelican Town or Cindersap Forest. (6:00 AM – 2:00 AM)


Found in the ocean at the Beach or Beach Farm. (6:00 PM – 2:00 AM)

Quest Rewards

Talk to Demetrius once you finish the task, and he will pay you exactly how much all the fish cost when shipped in the bin. Later, he will give the recipe for the Farm Computer. This quest can appear on the Special Orders board again, but you will only be able to get this crafting recipe once.

And that is all you need to do to complete the Aquatic Overpopulation quest. More fun and challenging quests are waiting to be fulfilled in Stardew Valley, so take on more quests to earn more valuable rewards!

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