Nets are useful tools for fishing. They function like a trap for fishing; one simply needs to set a net with the fishing skill menu and leave it for a few days, then come back to check it. Fish are usually caught after 1-2 days of leaving the net out. However, leaving it for slightly longer than 2 days causes the fish inside to rot, forcing the player to reset the trap. Nets can catch many low-quality fish such as roaches or perches, with one or two larger fish like salmon or trout. Nets must be set in deep water.
Nets cannot be made by the player, only purchased, usually from fishing equipment stores or general stores. Player will also start with 2 nets if they choose the "I want to be a fisherman." starting scenario. This makes it extremely useful, since nets are usually the only thing you will need to get an abundance of food at the start.
Nets will wear out over time, but it is a very slow process. You can see a bar behind the net, when its in your inventory, showing its status. Until now, players can not repair nets. But until you really cant use a net anymore, it has payed out itself lots of times.