The effects of the calcium concentration on chloride cell (mitochondria-rich cell) density in the gills of brown trout ( Salmo trutta L.) larvae were studied. For this purpose, animals were divided into 3 groups 2 weeks after hatching and each groups was exposed to different calcium concentrations of water for two weeks. The results showed that the number of chloride cells in gill arch epithelia of larval fish increased with decreased calcium concentration.This increase was statistically significant in the gills of larvae kept in zero-Ca 2+ freshwater (ZCWF) ( P< 0.001 ) and of those kept in low-Ca 2+ freshwater (LCFW) ( P< 0.05) in comparision with the gills of larvae kept in normal freshwater (NFW).

The effects of the calcium concentration on chloride cell (mitochondria-rich cell) density in the gills of brown trout ( Salmo trutta L.) larvae were studied. For this purpose, animals were divided into 3 groups 2 weeks after hatching and each groups was exposed to different calcium concentrations of water for two weeks. The results showed that the number of chloride cells in gill arch epithelia of larval fish increased with decreased calcium concentration.This increase was statistically significant in the gills of larvae kept in zero-Ca 2+ freshwater (ZCWF) ( P< 0.001 ) and of those kept in low-Ca 2+ freshwater (LCFW) ( P< 0.05) in comparision with the gills of larvae kept in normal freshwater (NFW).