Introducing Fish into Your Aquaponic System with a Salt Bath

Minerals found in water environment plays important roles in physiological functions in fish. In aquaculture production, salt which is a mineral in the form of sodium chloride (NaCl) has many positive applications. The raw material is affordable and available to many fish farmers. Salt bath is one significant application being practiced in the fish production industry. It is an immersion process of freshwater fish to salt solution at a prolonged time. This practice is usually done for the newly arrived fish stocks. The effectivity of this process could be influenced by the salt concentration, time of exposure and the fish species.

Benefits of Salt Bath

• Salt bath could improve the overall physiological condition of the stock fish.
• The procedure could cleanse the fish from possible pathogens or external parasites that they may be carrying from the source environment. 
• It could also stimulate mucus production due to stress during handling and transport. 
• Recovery of fish with skin wounds can also be improved through salt bath.

Per literature, a 3% salt dip for 30 seconds to 10 minutes could be effective in removing protozoa from the skin gills and fins of freshwater fish as well as improve mucus production.

Things to remember before doing salt bath

• have an accurate scale to weigh salt to have an exact final salt solution concentration
• know the water volume of your holding tank/ponds where you will do the salt bath
• it is better to try a trial test to few fish first before doing it to the it to the rest of the fish

Recommended salt concentration

• 0.1 - 1% (1,000 – 10,000 ppm) for stress fish during transport and handling
• 1 – 3% (10,000 – 30,000 ppm) for parasite infected fish for 30 minutes or until fish are stress (rolling over and imbalanced swimming)

Note: 1ppm is 1mg/liter. Salt sources are generally: table salt, meat-curing and rock salt.

Steps on doing salt bath

• Ready the hauling tanks/ponds with known salt concentration (0.1-3%) and aeration system.
• The salt must be totally dissolved using the water from the hauling tanks/ponds.
• You can check the salinity of the water of the hauling tanks using refractometer to verify the concentration.
• You must know the parameters such as water temperature and pH of the source environment and acclimatize the fish first to the new environment (hauling tanks/pond) accordingly to avoid further stress.
• Acclimation could be done by just allowing the stocked fish which are still inside the plastic bags float on the water surface of the hauling tanks/ ponds about 15 mins. Then, open the bags and allow the water from the hauling tank/pond to enter slowly into the bags until the fish will just swim outside of the bags.
• Just leave the fish in the salt solution at certain time up to 30 mins. If you observed that fish is starting to lose its balance and roll over, removed it right away from the tank/pond and transfer to clean freshwater tank/pond.