Swim bladder or fish maw is an internal gas-filled organ that contributes to the ability of many bony fish to control their buoyancy. In some Asian cultures, the swim bladders of certain large fishes are considered a food delicacy. In China they are known as fish maw and are served in soups or stews. Swim bladders are also used in the food industry as a source of collagen. It can also be made into strong, water-resistant glue, or used to make isinglass used in clearing up beer and wine during manufacturing.
Because of a growing demand in China the price of fish maw has gone up in recent years, this has opened up an export opportunity. According to Tridge South Africa only exports around $3.9M worth of fish maw while the booming trade in Uganda does around $88 million annually (I have not verified either number so they should be treated as ballpark figures).
Once regarded as waste, the bladder has to be sourced and dried to prepare it for export.
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