Beyond respiration, the gill is the fish’s primary chemical regulator. A fish’s body fluids are saltier than freshwater but less salty than seawater. In freshwater, water constantly rushes into the fish’s body through osmosis, threatening to dilute its blood. To counter this, the gill’s chloride cells actively pump in salt ions to maintain homeostasis. Conversely, in a marine environment, a fish is in constant danger of dehydration as water is sucked out of its body. In this case, the gill cells work in reverse, actively excreting excess salt. A marine fish essentially drinks seawater and relies on its gills to desalinate its blood, expelling the sodium and chloride ions back into the ocean. This osmoregulatory function is so demanding that it consumes up to 25% of a fish’s metabolic energy.
, specifically regarding their "Cuda 12 Build Up" or similar projects involving kayak fishing. fishgrs work