Sodium, potassium and chorine are found in the fluids and soft tissue of the body. They serve in regulating osmotic pressure and acid-base balance and also play important roles in water metabolism. These elements are closely related metabolically. Sources of sodium include crab meal, fish solubles, fish meal, krill meal and shrimp meal. Sources of potassium include dried distillers solubles, cottonseed meal, fish solubles, rice bran, soybean meal, wheat bran and yeast. Sources of chlorine include crab meal, fish solubles, fish meal and shrimp meal (Akiyama et al., 1992).

Recommended levels of sodium and potassium in commercial feeds are 0.6% and 0.9%, respectively. Chlorine levels are usually not limiting in feed formulations. Supplemented potassium sources include potassium chloride and potassium iodate. Salt (NaCl) may be supplemented at 0.2% as a flavor enhancer especially in high plant product formulations (Akiyama et al., 1992).