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11-03-2006, 02:12 PM

There are many types of “salts” but I assume you are talking about sodium chloride (NaCl), which dissociates into Na+ and Cl+ ions in solution. It will NOT add any other electrolytes to water nor will it increase dissolved oxygen in water. It is an irritant and will unnecessarily promote excessive mucus production in fish. There are many arguments against the use of salt as a general “tonic”.

1) Many experienced hobbyists believe that constant use of salt have resulted in more salt tolerant strains of parasites that require double strength dosages to treat.
2) Many species of catfish, tetras, loaches are intolerant of salt.
3) Fish that come from soft (low GH), acidic (low pH) water also come from water that’s very low in TDS (total dissolved solids). Salt dramatically raises the TDS of water even though it does not affect GH.

So unless your FRESHWATER fish are suffering from an illness (such as nitrite poisoning, parasites, bacterial/fungal infection), it is not needed nor is it recommended.

Salt will not prevent diseases. Proper quarantine, water quality and nutrition does.

The more salts (or any dissolved solids) in solution, the less dissolved oxygen capacity you will have.

Salts are absorbed by the gill membranes and into the bloodstream through osmosis (much the same way as dissolved oxygen). Freshwater fish have developed a highly efficient urinary system through many, many years of evolution which allows them to expel excess water in order for them to osmoregulate or else their system would be flooded with fluids (like dropsy). Their kidneys are so efficient that, even in water that's very low in TDS, they are still able to retain the salts in their body while excreting urea. Salt is not needed in a freshwater environment simply because nature has already found a way for these fish to survive without it.

That being said, salt is a very effective tool in fishkeeping. It will help prevent nitrite poisoning (but that's only when you are cycling a tank and there's nitrites present). It will also combat a wide range of ailments such as parasites and bacterial infections (but that's only when your fish have these ailments).

Just like in humans, salt is necessary to maintain body function (not just sodium salts). But even in rivers that are very low in dissolved solids and hardness, there are still trace amounts of salts in the water. The only reason why we would put salts and buffers back in is when we reconstitute R/O or distilled water.

From Aquaria Central :

QUOTE
The term osmosis is simply the diffusion of water. The gill membrane allows the passage of many different molecules. Sodium (Na+), chloride (Cl-), water (H2O), respiratory gases such as carbon dioxide (CO2) and others. When concentrated solutions move to lower areas in this way, no energy is expelled. This occurs via osmotic pressure and is called passive transport. Other factors in osmoregulation do require energy such as respiration, blood flow, kidney function, etc.. Even a seemingly resting fish is still expending a great deal of energy to maintain it's internal salt to water ratio. This is especially so in captive specimens due to the fluctuating salinity level of the home aquarium.

In order to simplify and properly explore the differences between fresh and saltwater fish, in regards to osmoregulation, we must address the two groups separately. Many substances are passing in and out of the gill simultaneously. As Na+ and H2O pass inward for osmoregulation, ammonium ions (NH4) and hydrogen ions (H+) pass outward. Freshwater fish face two problems: 1) getting rid of excess water and 2) maintaining proper salt content in their bodies. Their bodies need to maintain a higher level of salt than the surrounding water. As H2O passes in through their gill, Na+ is lost. To counter act this problem, freshwater fish drink constantly to maintain proper ionic levels. These ions obtained from drinking are transferred to the blood through the kidney via the "Bowman's capsule". Ions obtained through osmosis at the gill have a direct link to the blood via specialized "Chloride cells" in the gill. The efficient kidney enables the fish to excrete H2O very rapidly as a dilute urine. Na+ loss is greatly reduced by efficient reabsorption from the urine before it is excreted.

11-03-2006, 02:12 PM	#1
blacks Guest Posts: n/a	Use of salt There are many types of “salts” but I assume you are talking about sodium chloride (NaCl), which dissociates into Na+ and Cl+ ions in solution. It will NOT add any other electrolytes to water nor will it increase dissolved oxygen in water. It is an irritant and will unnecessarily promote excessive mucus production in fish. There are many arguments against the use of salt as a general “tonic”. 1) Many experienced hobbyists believe that constant use of salt have resulted in more salt tolerant strains of parasites that require double strength dosages to treat. 2) Many species of catfish, tetras, loaches are intolerant of salt. 3) Fish that come from soft (low GH), acidic (low pH) water also come from water that’s very low in TDS (total dissolved solids). Salt dramatically raises the TDS of water even though it does not affect GH. So unless your FRESHWATER fish are suffering from an illness (such as nitrite poisoning, parasites, bacterial/fungal infection), it is not needed nor is it recommended. Salt will not prevent diseases. Proper quarantine, water quality and nutrition does. The more salts (or any dissolved solids) in solution, the less dissolved oxygen capacity you will have. Salts are absorbed by the gill membranes and into the bloodstream through osmosis (much the same way as dissolved oxygen). Freshwater fish have developed a highly efficient urinary system through many, many years of evolution which allows them to expel excess water in order for them to osmoregulate or else their system would be flooded with fluids (like dropsy). Their kidneys are so efficient that, even in water that's very low in TDS, they are still able to retain the salts in their body while excreting urea. Salt is not needed in a freshwater environment simply because nature has already found a way for these fish to survive without it. That being said, salt is a very effective tool in fishkeeping. It will help prevent nitrite poisoning (but that's only when you are cycling a tank and there's nitrites present). It will also combat a wide range of ailments such as parasites and bacterial infections (but that's only when your fish have these ailments). Just like in humans, salt is necessary to maintain body function (not just sodium salts). But even in rivers that are very low in dissolved solids and hardness, there are still trace amounts of salts in the water. The only reason why we would put salts and buffers back in is when we reconstitute R/O or distilled water. From Aquaria Central : QUOTE The term osmosis is simply the diffusion of water. The gill membrane allows the passage of many different molecules. Sodium (Na+), chloride (Cl-), water (H2O), respiratory gases such as carbon dioxide (CO2) and others. When concentrated solutions move to lower areas in this way, no energy is expelled. This occurs via osmotic pressure and is called passive transport. Other factors in osmoregulation do require energy such as respiration, blood flow, kidney function, etc.. Even a seemingly resting fish is still expending a great deal of energy to maintain it's internal salt to water ratio. This is especially so in captive specimens due to the fluctuating salinity level of the home aquarium. In order to simplify and properly explore the differences between fresh and saltwater fish, in regards to osmoregulation, we must address the two groups separately. Many substances are passing in and out of the gill simultaneously. As Na+ and H2O pass inward for osmoregulation, ammonium ions (NH4) and hydrogen ions (H+) pass outward. Freshwater fish face two problems: 1) getting rid of excess water and 2) maintaining proper salt content in their bodies. Their bodies need to maintain a higher level of salt than the surrounding water. As H2O passes in through their gill, Na+ is lost. To counter act this problem, freshwater fish drink constantly to maintain proper ionic levels. These ions obtained from drinking are transferred to the blood through the kidney via the "Bowman's capsule". Ions obtained through osmosis at the gill have a direct link to the blood via specialized "Chloride cells" in the gill. The efficient kidney enables the fish to excrete H2O very rapidly as a dilute urine. Na+ loss is greatly reduced by efficient reabsorption from the urine before it is excreted.