The fishing industry includes any industry or activity that takes, cultures, processes, preserves, stores, transports, markets or sells fish or fish products. It is defined by the Food and Agriculture Organization as including recreational, subsistence and commercial fishing, as well as the related harvesting, processing, and marketing sectors. The commercial activity is aimed at the delivery of fish and other seafood products for human consumption or as input factors in other industrial processes. The livelihood of over 500 million people in developing countries depends directly or indirectly on fisheries and aquaculture.

The fishing industry is struggling with environmental and welfare issues, including overfishing and occupational safety. Additionally, the combined pressures of climate change, biodiversity loss and overfishing endanger the livelihoods and food security of a substantial portion of the global population. Stocks fished within biologically sustainable levels decreased from 90% in 1974 to 62.3% in 2021.

The industry has three principal sectors that include recreational, subsistence or traditional, and commercial fishing.

Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions. Large-scale commercial fishing is called industrial fishing.

The major fishing industries are not only owned by major corporations but by small families as well. In order to adapt to declining fish populations and increased demand, many commercial fishing operations have reduced the sustainability of their harvest by fishing further down the food chain. This raises concern for fishery managers and researchers, who highlight how further they say that for those reasons, the sustainability of the marine ecosystems could be in danger of collapsing.

Commercial fishermen harvest a wide variety of animals. However, a very small number of species support the majority of the world's fisheries; these include herring, cod, anchovy, tuna, flounder, mullet, squid, shrimp, salmon, crab, lobster, oyster and scallops. All except these last four provided a worldwide catch of well over a million tonnes in 1999, with herring and sardines together providing a catch of over 22 million metric tons in 1999. Many other species are fished in smaller numbers.

Fish are harvested by commercial fishing and aquaculture. Stocks fished within biologically sustainable levels decreased from 90% in 1974 to 62.3% in 2021.

The world harvest increased over the 20th century and, by 1986, had stabilized around 85–95 million metric tons (94×10^⁶–105×10^⁶ short tons) per year. According to the Food and Agriculture Organization (FAO), the world harvest in 2005 consisted of 93.3 million metric tons (102.8×10^⁶ short tons) captured by commercial fishing in wild fisheries, plus 48.1 million metric tons (53.0×10^⁶ short tons) produced by fish farms. In addition, 1.3 million metric tons (1.4×10^⁶ short tons) of aquatic plants (seaweed etc.) were captured in wild fisheries and 14.8 million metric tons (16.3×10^⁶ short tons) were produced by aquaculture. The number of individual fish caught in the wild has been estimated at 0.97–2.7 trillion per year (not counting fish farms or marine invertebrates).