The Use Of Salt
Submitted by: dnalex
Salt is a major staple in every goldfish keeper's supply kit, and it is
often used as a first line defense against a host of goldfish problems.
Salt can be antimicrobial, promotes healing and slimecoat, and can help
relieve osmotic pressure ("breathing"). Trinket, one of our esteemed
moderators, wrote on the use of salt here.
Because salt occupies such a prominent place in our medicine cabinet,
and because the misuse/abuse/prolonged use of salt can lead to a host of
problems not unlike the things we are trying to cure, I thought to
revisit this topic and expanded a little bit on what Trinket had laid
out for us, namely to discuss the use of the specific salts and how to
properly measure the amount of salt we need.
1. What type of salt can be used safely?
As Trinket had said in her post, any salt that does not contain
additives (including yellow prussiate of soda, anti-caking agents,
minerals, or iodine) is ok for use in our aquariums. Most commonly, this
translates to using aquarium salt (some manufacturer include API and
jungle). Aquarium salt usually comes in larger grains. Additionally,
Morton's Canning & Pickling salt has been found to be safe and effective
to use. Morton's C&P salt comes in a four pound box (all green or
blue/green) and can be found in the salt section of many grocery stores
in the United States. Morton's C&P salt is very fine grain (looks more
like table salt), and is usually the cheapest option available. The C&P
salt is often times 5-10x cheaper than aquarium salt. A box of Morton's
Canning & Picking Salt looks like this
2. Dosages of salt & how to add salt to the tank
Depending on the situation, you'll be using 0.1%, 0.2%, or 0.3% salt to
treat your fish. However, to prevent osmotic shock to fish and to
minimize salt's effect on the tank's cycle bacteria, salt is only added
at 0.1% increments every twelve hours to the 0.3% salt maximum. You
should never just dump salt grains into the tank. When you do that, your
fish will most likely rush to the salt and try to eat it. Salt granules
can be very irritating/damaging to fish gills, so you should always
dissolve the salt first before adding to the tank. The easiest (and
quickest) way to do this is to take some tank water (or de-chlorinated
water) and heat on the stove top. Once the water is hot/boiling, you can
add the necessary amount of salt to dissolve, let cool to the same
temperature as the tank temp, and add to the tank. [10/13/2013 edit: I
have found over the last two years that actually, the easiest, and
probably better, way of dissolving salt is to put the amount of salt you
need into a pantyhose/nylon mesh, tie it up, hang it in the tank, and
let it slowly dissolve. This way, you won't have to fuss with dissolving
it first, and the salinity is brought up more slowly, which is less
shock for the fish.]
3. How to correctly measure out salt for use
Using teaspoons per gallon 0.1% salt is 1 teaspoon of salt per gallon.
However, because we never fill our tanks to 100% capacity, always
estimate the water volume to be a little bit less than your actual tank
size (9 gallons for 10g tank, 18 gallons for 20 gallon tank, and so on).
This measurement calls for using level teaspoon, not rounded teaspoon.
Also, if you are using Morton's Canning & Pickling Salt, 0.1% salt is
actually 3/4 teaspoon per gallon, since the Morton's salt grains are
much finer, and so you actually get a lot more salt per teaspoon of
Morton's than compared to the larger grained aquarium salt.
Metric system and the scale 0.1% salt is 1g/liter of tank water. There
are 3.79 liters in a gallon. So, whatever size your tank is in gallons,
multiply that by 3.79, and that is how many grams you need in order to
raise the salinity of your tank to 0.1%. Here are some common sizes and
the amount of salt you will need to raise the salt by 0.1%
- 10 gallons = 10x3.79 = 37.9 grams of salt to increase salt
concentration to 0.1% - 20 gallons = 20x3.79 = 75.8 grams of salt to
increase salt concentration to 0.1% - 29 gallons = 29x3.79 = 109.9 grams
of salt to increase salt concentration to 0.1% - 55 gallons = 55x3.79 =
208.5 grams of salt to increase salt concentration to 0.1% - 75 gallons
= 75x3.79 = 284 grams of salt to increase salt concentration to 0.1%
If you need to raise salt to more than 0.1%, then you will want to
dissolve and add the correct amount of salt to your tank 12 hours later,
and so on. If your tank is already in liters, than the size of your tank
is the amount of salt you will need, in grams, to raise the salinity to
0.1% (a 750L tank will need 750 grams of salt to be at 0.1%).
4. The duration of salt use Depending of the situation, you may be
advised (or have elected) to salt your tank(s) anywhere from a few days
up to a maximum of four weeks.
5. The consequences of prolonged salt usage This question has been
raised many times - if salt can be so beneficial, why not just keep it
in the system for longer than four weeks? There are a couple of
important reasons why salt should not be used for long durations. First,
like any other treatment, prolonged exposure can lead to tolerance in
the case of bacteria and other pathogens, and then salt is no longer
effective. Unfortunately, this has already happened because of some very
irresponsible breeders/farmers who have kept their fish at low levels of
salt. A prime example of this flukes. Flukes used to be very treatable
with salt. However, at present salt is no longer very effective against
flukes, and we have to resort to other means, such as praziquantel.
Another reason why prolonged use of salt is discouraged is because
chronic salt exposure could lead to development of what is called
osmotic stress in fish. Fish experiencing osmotic stress may display the
following symptoms: clamped fins, disequilibrium (unable to balance
itself), excited behavior (darting), lethargic (floating), rapid
breathing, faded colors, salt burns as evidenced by blackened areas, and
6. Salt for protection against nitrite. (edit by Shakaho 8/22/2017)
Whenever you have a nitrite reading above zero, you should add salt to
protect the fish from nitrite poisoning. It only requires 1 teaspoon of
salt per ten gallons of water. This will not lower the nitrite reading.
Maintain this salt concentration until the nitrite reads zero
Writen by dnalex