SALINITY INDUCED CHANGES TO THE SURVIVAL, GROWTH AND GLYCOGEN DISTRIBUTION OF SILVER BARB, Barbodes gonionotus (BLEEKER, 1850) EARLY FRY

Salinity is one of the most important abiotic factors for the survival and growth of fish, and the optimal range is highly dependent on the species as well as life stage that tends to increase with ontogentic development. In some hatcheries, slightly saline water (≈ 1 - 3 ppt) is used to minimize diseases while salinization of freshwater ecoystems is becoming a greater issue.  To date, there is no information on the effects of salinity to silver barb Barbodes gonionotus early fry despite their high commercial value throughout the Indo-Pacific region.  This study assessed the survival, growth and glycogen distribution in the gills, intestine and liver of B. gonionotus early fry for 17 days when subjected to salinities of 0, 3, 6 or 9 ppt.

Results showed that growth significantly decreased after 17 days for fish at 3 ppt and above.  Survival and condition factor significantly decreased and increased, respectively, only for fish at 9 ppt.

Glycogen-rich mucous cells in the gills were less at 9 ppt (Fig. 1b) compared to at 0 (Fig 1a), 3 or 6 ppt.  In addition, the liver and intestine of fish at 9 ppt had less glycogen compared to the other treatments.

Results indicate B. gonionotus early fry are highly sensitive to increase salinities, evidenced by a reduction to growth and glycogen distribution which suggests increased energetic demands for osmoregulation.  This study should prompt further studies regarding the vulnerabilities of young fish inhabiting freshwater areas experiencing salinization.