EVALUATION OF TWO SALT TREATMENTS FOR HOLDING MARKET SIZE LARGEMOUTH BASS Micropterus salmoides AS A FOOD FISH

Distributing locally grown food fish live may provide aquaculture producers in Kentucky a more profitable market opportunity than selling fish as a commodity.  Routinely holding fish live in recirculating systems with minimal loss will be required for this pathway to be successful.  In this study investigators evaluated the use of salt in recirculating systems for holding unfed market size largemouth bass. Two experiments were conducted and two treatments per experiment were evaluated: 1) 0 and 4 parts per thousand (ppt.) NaCl; 2) 4 and 8 ppt.  Water quality was monitored daily, and blood chemistry was analyzed at 0, 48, 96, 144, and 192 hours after stocking. Blood chemistry was measured with the Abaxis Vetscan VS2 analyzer.

In experiment 1 (0 & 4 ppt. NaCl), total ammonia nitrogen (TAN), un-ionized ammonia (UIA), nitrite and nitrate increased over time.  There was a decrease in pH of the water after hour 0.  Differences between treatments were found for TAN, UIA, and pH. In the blood, Albumin, Globulin, and Total Protein increased from  hour 0, then remained elevated throughout the experiment.  Phosphorus and the enzyme Alanine Aminotransferase (ALT) decreased over time, while blood glucose was highest at hour 0, then decreased and stabilized.  Treatment effects were found for blood sodium and plasma cortisol.

In experiment 2 (4 & 8 ppt. NaCl), nitrate increased over time; pH of the water decreased at hour 0; and treatment effects were found for nitrite, TAN, UIA, and pH.  Blood chloride and sodium increased over time, while calcium, potassium, and the enzymes Alkaline Phosphatase (ALP) and ALT decreased.  The enzyme AST and blood CO₂ changed over time as well.  Blood glucose was greatest at hour 0, then decreased and stabilized.  Treatment effects were found for chloride and CO₂.  

There was no apparent weight loss or mortality in either experiment.  In both experiments water pH, blood glucose, ALT, and decreased and nitrate increased.  There were salinity treatment effects for TAN, UIA, pH, and sodium in both experiments.