Freshwater fish constantly take in water and excrete dilute urine, while marine fish drink seawater and expel concentrated salts—chloride cells in their gills actively pump ions to maintain this balance. Migratory fish like hilsa and salmon undergo smoltification, reprogramming these cells to switch between systems. But watching our local brackish water ponds, I've seen hilsa adapt faster than any textbook says—they're not just switching systems, they're holding both in readiness, like my fingers that can still stitch a fine *kashta* after years of saltwater sampling.
#surfing#mulki
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