Some of the quests in Escape from Duckov have you exploring the Ground Zero map to learn the basics of the game. Later on, you will encounter several fishing quests that require you to craft fishing rods and find suitable spots to fish. This guide will detail how to go about doing that in the game.
Escape from Duckov Fishing Guide

To craft a fishing rod, first upgrade your Workbench by unlocking Advanced Progression II and get the recipe. After unlocking the recipe, you will require 2x wood and 1x steel to craft the fishing rod. These are common resources that you get in the early game. Next, head over to the Workbench and select the crafting recipe for the Fishing Rod, then add this equipment to your melee slot from your inventory.

Now, collect bait either in the overworld or by purchasing the Bait recipe from Vogo. Purchasing the recipe is a bit expensive; you are better off scavenging for bait. Get a shovel and explore digging spots that appear randomly on the map. There is a chance to get bait this way for free. Interact with the fishing rod in your inventory to add bait. Later on, besides worms, you get to also add batteries and other items as bait to lure in unique items from the water.
How to Fish

To start fishing, press F once you reach the pier to cast your line. This will start a mini-game, which is simple to follow. You will spot two circles in the mini-game. The bigger circle will start getting smaller, while the smaller circle of the two stays as-is. Wait for the bigger circle to overlap the smaller circle, then press the Spacebar to reel in the line. If you press it too fast or too slowly, you will lose your bait and get nothing.
All Fishing Locations

There are two fishing spots where you get to cast your line. The first area is south of North Mountain, and the second spot is near Road Camp. The one at Road Camp is slightly more difficult to fish in peace, you will likely keep getting interrupted by high-level enemies. Be prepared with your best weapons and armor if you wish to fish here.
How to Upgrade Fishing Skill

Speak to Vogo after unlocking the Kitchen to find the Fishing Skill Upgrades. There are several fishing upgrade tiers to unlock, and each unlock requires credits and certain fish types. Upgrading the fishing skill will increase your fishing ability, helping you catch better fish and reducing the time taken.
Also, there are quests related to fishing given to you by Vogo, and they are worth picking up for rewards and additional knowledge on fishing.
How to Store Fish

Since fish will take up slots in your warehouse and backpack, you can craft barrels to store fish. Head over to your Workbench to find crafting recipes for Red, Blue, and Yellow barrels. Each barrel offers different storage capacities to store fish. While you are out fishing, use the barrel for storage to free up space. Fish can be sold or used in certain recipes after unlocking them in Escape from Duckov.

