What’s Your Opinion About Aquarium Salt!
Text by Majid Ali  (Ryedale AS)
This article was written for the Ryedale Reporter - the monthly magazine of the Ryedale Aquarist Society

Aquarium salt, which has been scientifically proved to be of benefit to both aquariums and their livestock, is an ingredient that has been used for many years now and has proven its worth in our hobby.  You could say for fish it’s the equivalent to the natural healing medicine ‘Aloe Vera’, although several Aquarists’ I know claim its closer to a painkiller?
Before going any further I must mention that (as far as I am aware), there are two types of regular salts available for aquarium use, which are:  
1. Tonic salt (aquarium salt): composed of sodium chloride which is used more for treatment and/or for sterilizing aquariums (as stated on some salt products, depending on the company).  
2.  Marine salt: is more complex containing magnesium and calcium, which provides good water conditions for invertebrates.
Photograph by David Marshall
Tropical marine fish need high concentrations of salt in their aquariums. I for one am definitely in favour of using aquarium salt, when required, and here are some proven benefits of using it:   Reduces toxicity - Salt reduces nitrite levels for freshwater fish. The sodium and chloride will reduce nitrite levels in aquariums and studies in the past have shown that chloride reduces nitrite by providing the ions, which offer fish a form of protection against the nitrite. Attacks parasites and pathogens - Salt kills parasites like Trichodina and pathogens.  The old fashioned, but very workable, method of curing fungus infections on fish.

Photograph by Arthur Frisby.
White Cloud Mountain Minnows are prone to velvet disease (Piscinoodinium). Tonic salt is a safe medication for the cure of this malady. Osmoregulation - Another word for the physiological device fish use to manage the amount of salt and fluids in their bodies. Freshwater fish are more saltier than the water they live in and their skin is semi-permeable so, particularly when stressed, they can suffer from osmoregulatory dysfunction i.e. starting to lose bodily salts and this loss can be reduced through the use of aquarium salt.   Transporting fish - Salt can be used to reduce stress on fish when they are moved   from one location to another.    Things to remember:   Some aquatic companies recommend the use of salt as a regular routine, although opinions differ.   Some Aquarists’ add tonic salt to their aquariums once every 2-3 months, whereas others use it only when necessary. 3. Some species of freshwater fish, in particular ‘Hoplosternum’ catfish, are not  tolerant of salt in their surroundings.  Others, in particular the livebearing Goodeids of the Mexican plateau, have great need of tonic salt in order to maintain their health.   Never use domestic table salt in aquaria as this contains additives that are toxic to fish. 
Photograph by David Marshall 
Cichlids from Lake Malawi are used to the high mineral content of their natural waters but over use of aquarium salt with these fish can cause the malady ‘Malawi bloat’.