Sometimes our IBC members post content on Facebook that is too good to pass up.

Member CJ Cowan posted this interesting piece on the use of aquarium salt, we have reproduced it here with CJ’s permission.


Photo By Edal Anton Lefterov (Own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons

Using aquarium salt should be considered if you like to keep your betta healthy. I realize this can still be considered controversial, however through research and practical application the positives far outweigh the negatives if used properly. It is an inexpensive preventative that does not harm the beneficial bacteria in your tank or plants when used at the recommended dose. Aquarium salt does not contain iodine like table salt or trace mineral like sea salt. Most tap water has an extremely low level of salinity. The rivers in Thailand do not flow with North American tap water and once chlorine is gone via dechlorinator—it’s a party for bacteria in tap water. By adding aquarium salt we are actually recreating the betta’s natural habitat conditions. The natural Thailand environment of betta has a wide range of salinity, from very low to brackish depending on location or proximity to the Gulf of Thailand which is a salt water environment with fresh water flow. Thus betta have a high tolerance to salinity variance developed over millions of years. Most bad bacteria have little or no ability to adapt to changes in salinity and will literally burst cells causing death.

Aquarium Salt can:

  • Aid in the control of many parasitic and pathogen populations including Ich and velvet.
  • Enhance the fish ability to produce a good protective slime coat. Very helpful if the fish is recovering from a bacterial infection, injury, torn or bitten fins and often fin rot.
  • Prevent intake of lethal nitrates during nitrogen cycling of a new tank.
  • Prevent intake of stressful high nitrates in existing cycled aquariums.
  • Lessen the fish stress levels by aiding the gill function.
    • Fish kidneys are designed to excrete water absorbed through the skin and gills. This is a major and important job. By adding aquarium salt the fish kidneys do less work because the amount of water absorbed into the blood via the gills is reduced.
  • Adds needed electrolytes to the water.
    • Osmoregulation is basically the maintaining of a proper fluid-electrolyte balance in the body fluids of fish. Osmosis is the tendency of water to travel through a semi-permeable membrane from an area of high electrolyte concentration. Why is this important to the fish?  First of all, blood and body fluids contain several electrolytes. For ease in discussion, we will say salts. The concentration of salts in the body fluid of freshwater fish is much higher than their surrounding water. A fishes’ gills are a perfect example of semi-permeable membrane. Water from the outside wants to go through the gills- to inside- and does, in large quantities. If this went on unchecked, the internal body fluids of the fish would become severely diluted and suffer an intolerable electrolyte loss through elimination. Freshwater fish deal with this problem in several ways. When there is plenty of oxygen in the water, they cut down on respiration and cut water influx through the gills. (This is one area where low dissolved oxygen can cause a fish a lot of problems). The other way fish deal with this problem is through cells clustered around the base of their gill filaments. These are called chloride cells. These cells require energy from the fish to work. They can transport sodium and chloride ions (against the flow, so to speak) from the water outside, to the blood inside. This replaces electrolytes lost by the production of the large amount of urine excreted. If there is too little sodium and too few chloride ions in the water, the chloride cells must work too hard to do their job, which causes more stress on the fish.
  • The un-ionised form of the ammonium ion (NH3) is the most toxic. The toxicity of ammonia to aquatic life is affected by the following physico-chemical parameters: temperature, pH, dissolved oxygen and salinity. In general, ammonia toxicity is greater, the higher the temperature and pH and the lower the levels of dissolved oxygen and salinity.

At high concentrations like 1-3 tablespoons per gallon, aquarium salt can keep nets and gravel vacuums from spreading pathogens tank to tank. I keep a separate bucket at high salinity for any equipment that is shared in the fish room. The concentration of the salt is based on intent.

As a general rule of thumb start with 1 tablespoon per 5-7 gallons of aquarium water. This is a safe dose for all fish and plants including salt sensitive corydoras. Some betta keepers only use aquarium salt as a general tonic or preventative. Others use it at higher concentrations to treat for existing parasites, but remember it is not a cure all and can be combined with other things like methylene blue or antibiotics outside of the aquarium in a fish bath to treat stubborn or difficult pathogens. If treating an existing problem the use of high concentration via fish bath should only be done outside the aquarium in a container and last only minutes. You may have read that aquarium salt will cause issues with kidney and liver. This is only true if used at a high level for a prolonged period of time which is never recommended.

Bacteria and parasites do not gain resistance to salt like they can with antibiotics. The benefits are many but there are drawbacks to consider. Live plants can be killed if concentrations are too high as well as corydoras and Chinese algae eaters so try to stay at the recommended levels if using in the aquarium. Bottom feeding fish can adjust to a low dose salt level if salt is slowly added over a few days. Avoid dumping all the salt at one time and always pre dissolve the salt before adding especially if the tank has salt sensitive species.

Many people think salt is salt—nope, it comes in many forms. Iodized table salt can cause ammonia levels to rise then nitrites. This can cause major upsets in the aquariums biological filtration bed. Sodium Chloride does not dissipate, only water changes will remove salt. If you are using aquarium salt (NaCl) in your 20 gallon aquarium and you change 5 gallons of water you need ONLY add salt for the 5 gallons changed, not the 20 gallons of aquarium water otherwise your salt levels will build up with time.

My own experience has been that my fish are way healthier, vibrant and much less prone to diseases. Have you ever noticed how salty human skin is? This helps us prevent skin infections much the same way, we would have itchy infected skin constantly without it. Who uses aquarium salt? My friend who has a large aquarium shop with over 300 species of fish and in business over 20 years. He uses 1 tsp per 5 gallons in all his water to prevent outbreaks that could destroy many valuable fish. Many Thai breeders who already have a higher salinity in the water than our tap water and many top North American breeders.

Feel free to comment below and continue the discussion.