Salt Use to Reduce Stress
Chemical Additives
• Anesthetics – calm excitable fish
• Salts reduce stress
(osmoregulation)
Transport Stress
• Netting
• Handling
• Travel
Blood Salt Leakage
• Gradient between blood and
environment (water)
• Loss of mucous layer
• Transport stress (crowding,
jostling, water quality)
• Muscle, nerve, heart and kidney
effects
Minimizing Salt Loss
• Traditional, add 0.5-2.0 g/L (0.050.2 %) sodium chloride
• Reduces salt loss
Vertebrate Blood
• 9 g/L or a 0.9 % salt solution
• pH 7.4
• 77 % of salts are sodium and
chloride, table salt (NaCl)
• Other major salts include
bicarbonate, potassium, and
calcium
Vertebrate Blood Salts: ECF
Salts
ECF (g/L)
Sodium
3.27
Chloride
3.65
Bicarbonate
1.71
Potassium
0.20
Calcium
0.10
0.8 % NaCl Solution
• An 8 g/L (0.8 %) salt solution
matches blood sodium content
• 8 g/L NaCl prevents sodium and
chloride loss
Advantages of 8 g/L NaCL
•
•
•
•
Slightly lower than 9 g/L
Keeps kidneys active (fluid loaded)
Prevents dehydration & shock
Minimizes salt loss
Vertebrate Blood Salts: ECF
Salts
ECF (g/L)
Sodium
3.27
Chloride
3.65
Bicarbonate
1.71
Potassium
0.20
Calcium
0.10
Table 1. Types, concentrations and quantitiesa of
food grade salts used in live fish transport water.
Chemical name
Concentration
Pounds per
100 gallons
Sodium chloride
8 g/L
(0.8% salt)
6.4
Calcium sulfate
125-250 mg/L
(as CaCO3)
0.18-0.36
Sodium bicarbonate
100-200 mg/L
(as CaCO3)
0.14-0.28
a
Assumes a starting concentration of zero (none present).
Wurts, W.A. 1995. World Aquaculture, 26(3): 80-81.
Increasing Calcium Hardness
• Add “food grade” calcium sulfate
or “agricultural” gypsum
• 125 – 250 mg/L
• Osmoregulation & stress – salt
balance
Increasing Alkalinity and pH
• Add sodium bicarbonate (baking
soda)
• 100 – 200 mg/L
• Improves buffering capacity
Potential Salt Additive
• Potassium: ECF = 195 mg/L
• Important for normal heart, nerve,
and muscle function
• Osmoregulation
• Caution
Salinity Tolerance?
• 24 to 48 hour bio-assay
• If in doubt, use water similar to
preferred environment
On-line Presentations
www.ca.uky.edu/wkrec/WurtsPrespage.htm
On-line Literature
www.ca.uky.edu/wkrec/WurtsLitpage.htm
Extension
Aquaculture
Specialist
Dr. Bill Wurts
Kentucky State
University CEP