Saturday, June 15, 2013

Salt and Cyprinus Carpio & Carassius Auratus.

   Cyprinus Carpio (Koi) and Carassius Auratus (goldfish) Cyprinidae are euryhaline in nature, or tolerant of a wide range of salinity, but this is only far short periods. With over, 1400-documented carp like fishes, it is today one of the largest family of all fishes. Carp are found in large areas of Asia as well as throughout North America and Africa. They are nonexistent in Australia and South America and are almost exclusively a fresh water genus.

With over, 1400-documented carp like fishes, it is today one of the largest family of all fishes. Carp are found in large areas of Asia as well as throughout North America and Africa. They are nonexistent in Australia and South America and are almost exclusively a fresh water genus.

     There are only a few exceptions to this rule, which are able to tolerate brackish water conditions. One, a far-eastern Red-fin, can contend with difficulties with salinities equal to that of salt water.

     Some pond hobbyists have a predilection about salt and believe that their fish do better with it, and add it whenever they do a water change. The fact is, salt is a known infection preventive on wounded fish, but it is not a panacea. Salt is also added to ponds to replace electrolytes (as sea salt), such as potassium, sodium, chloride, calcium and magnesium these are all removed from water by chloride cells located in the gills of the fish. Electrolytes are chemical compounds that separate into ions in solution, which is essential for the uptake of oxygen and the release of carbon dioxide and ammonium across the gill membranes. Cyprinid seem to have no problems acclimating to salt levels of two and one-half pounds per 100-gallons (378.5-liters) of pond water (2.5 lbs. or 1.13kg)/100gal. [378.54 liters] = 3.125 ppt.), they also have the primary characteristics of homeostasis, which is to maintain a constant internal environment in the face of changing external factors.

    Cyprinid in a hypo-osmotic medium like salt in the pond (aka: Brackish Water) maintains higher concentrations of water and lower concentrations of ions than are in the surrounding fluids. This creates a concentration gradient, and this results in osmosis; the transportation of waters out of the fish’s body. The Koi respond by drinking more water (Note: Freshwater fish do not drink water; they take it in through the process of osmosis. Thus, they are dependent on the level of dissolved solids in their surroundings to help them maintain a healthy electrolyte-to-water balance) than it would in an isotonic solution. Koi absorb most of the water they need through their skin by osmosis (is the net movement of water through a selective permeable membrane from a region of low solute potential to a region of high solute potential due to their hyper osmotic environment), not through their gills.

    Because most freshwater fish cannot drink their surrounding water (There are some exceptions to this rule like Salmon), when you place these freshwater fish in saltwater, they dehydrate. The gut along with dissolved ions like sodium, potassium, and chloride absorbs the excessive water swallowed. The excessive ions are secreted out of the body by chloride cells that are embedded in the gill epithelia. Their cells must always be bathed in a solution having the same osmotic strength as their cytoplasm. This is one of the reasons why fish and other animals have kidneys. The process of regulating the amounts of water and mineral salts in the blood is called: Osmoregulation.

Saltwater fish drink and retain water, but freshwater fish have the opposite problem; they must get rid of excess water as fast as it gets into their bodies by osmosis. In some freshwater fish, a higher electrolyte level (particularly of sodium chloride, calcium and magnesium) will help pull fluids through the body which also stimulates the natural mucous coat on fish to resist parasites, bacteria, and fungus. This process has a downside, resulting in the loss of many electrolytes, however. Some of these trace elements can be replaced by ions contained in fish food, but by far the most common method is through the movement of a substance against an osmotic gradient using energy. This usually involves the exchange of one substance for another. In the case of freshwater fish, Na+ (sodium) ions are taken from the water and ammonia ions are taken from the fish and they are exchanged. This effectively rids the fish of ammonia, but Koi have no problems ridding themselves of ammonia (unlike sharks) without any help from us.

    Chloride ions are exchanged for carbonate ions, which helps in maintaining the pH of the body fluids. This is just another reason that adequate calcium, (as in total hardness [GH], carbonate, [as in alkalinity (KH)], and electrolytes levels are very important.

Generally salts (trace elements), not just sodium chloride can affect osmosis. Magnesium can also play a paramount role as well. Calcium can affect and just as importantly be affected by proper osmotic function. Sulfates have been shown effective in improving nutrient absorption and toxin elimination. Magnesium (found in Laterite) plays a role in the activity of more than 325 enzymes and aids in the proper assimilation of Calcium.
However, for our Koi, the downside of adding salt is: Its metabolic rate will unquestionably increase with the addition of salt into the pond. The prolonged usage of such, stresses the Koi besides increases their metabolic rate dramatically, shortening a Koi’s life span. When the metabolic rate of the Cyprinus Carpio increases, its demand for oxygen (Carp are capable of tolerating dissolved oxygen levels as low as 0.04 percent, two examples are Carassius carassius and Tinca tinca) also increases; this places unneeded stress on the pond animals1.

    You may have noticed that the people that use salt in their ponds will have to add air stones or some other means of agitating the water to increase oxygen concentration. A word of caution though, too much aeration especially from Venturi may cause emphysematous in fish. The amount of oxygen that can be dissolved in water decreases as temperatures and salinity increase. Adding salt to the pond also hinders plant growth, upsets the natural balance of the pond and increases the conductivity3. If you have to add salt to your pond, then you are only adding a Band-Aid to a problem that exists, instead of fixing the problem.

    If you are adding physiological salt for high nitrites (NO2) then, your filter is grossly inadequate for your pond needs. A nitrite reading of .2-ppm is very serious, especially at elevated temperatures and high pH levels (which by the way might otherwise be “acceptable”). When the nitrite levels are above zero in bulk water, methmeglobin forms in the fish’s blood that prevents it from delivering oxygen to its cells, resulting in nitrite toxicity (methemoglobinemia). Ironically, the remedy for this is salt2. The chloride ions in salt reduce and/or hinder the toxic effects of nitrites.

     However, for more important than adding salt to ones pond, is to have a proper Redox Potential, which describes the ability for the loss of an electron by a molecule, atom, or ion to the gain of an electron by another molecule, atom, or ion. Without this reducing Redox Potential, many minerals cannot be absorbed and properly assimilated. So it is very important to keep a “positively charged” pond or Redox Potential of approximately 250-300 mV via proper dissolved oxygen levels, calcium and other electrolytes, proper cleaning procedures and water changes and UV Sterilization can help, too.
In other words, “Don’t fix the problem just cover it up with sodium chloride.” Moreover, adding the salt may imbued you into a “false sense of security” that you did something to help the fish, when the salt could be irrelevant.

   This misguided sense of security that you have done something decent, may impede you from any further efforts to discover the actual problem and increase the likelihood that all the fish will get sick and/or pearish, and you will have learned nothing in the process.

   I do not think this kind of carpe diem methodology makes for good husbandry of pond keeping. However, then again many people think salt makes an excellent blanket to cover up their crimes. 

1: Undergraduate students from the University of Michigan have conducted an assortment of scientific research on salinity tolerance of Cyprinid. The experiments performed were to gather information involving salinity tolerances and preferences. The metabolic rate of Cyprinid was measured at 10-ppt sodium chloride levels (saltwater aquaria has a specific gravities of 1.020-1.025, which is about 27.30-33.75ppt.) and their metabolic rate in freshwater was to be their comparison. It was establish that at 18o C. (65o F.); Cyprinid would need a hundred percent more oxygen per milligram of body weight than it would in just plain freshwater. In many books and magazines, it states, “The salt will also help relieve some of the metabolic stress on the fish so its immune system can fight off bad bacteria.” This statement by the studies conducted by the undergraduates is very misleading and inaccurate. Metabolic rates of Cyprinidae do not decrease, but increase, as salt concentrations elevate. After all what animal currently: Breathes heavier, drinks water continuously, when it normally doesn’t drink water at all and needs more oxygen too sustain itself when it is supposed to be “relaxed”?

2: The myth of using table salt with iodine is harmful to fish is taradiddle. Iodine in table salt is harmless to fish, and may even be helpful. In the Marine aquarium hobby, reef tank aquarists are using iodine supplements for improved growth of their corals without adversely affecting the fish’s health in any way, shape, size, or form. The fact is sea salt already has iodine added in it as part of one of the trace elements.

3: The ability of a solution to conduct electric current depends on the concentration of ions in the solution. For example, drinking water drawn from a typical municipal treatment plant in the United States contains few ions and therefore is a poor conductor of current. However, seawater and brackish-water, the environment that we create in our ponds, with significant amounts of dissolved sodium chloride, magnesium sulfate, and other ionic compounds, is a good conductor. Experiments conducted on saltwater and freshwater fish have shown signs of sickness, (e.g., such as lateral line disease in saltwater fish) with just small amounts of electrical current, being given off by submersible pumps, UV-Lights, external pumps, and heaters. These items may become inconspicuous electrical outlets in our ponds. This can be a contribute to Koi and goldfish diseases and problems, such as lacerations or ulcerations on the skin, swim bladder, and Dropsy. The hobbyist may not know this; do to the fact that they will not receive an electrical shock from these items themselves, because of the infinitesimal amount of electrical current, read in millivolts (mV), that these items give off. Long-term use of Sodium Chloride should be looked at with a grain of salt (no pun intended). 

Formula for Salt in Koi Ponds:

1.0 lbs salt/100 gal = 1.25 ppt (parts per thousand) 1.5 lbs/100 gals = 1.88 ppt
2.0 lbs/100 gals = 2.5 ppt
2.5 lbs/100 gals = 3.125 ppt
For amount of salt to add to get to a desired concentration in ppt:
Lbs salt to add = (total gallonage of your system/120) multiplied by (desired salt concentration in ppt - current salt concentration in ppt)
For example:
Pond system volume: 4400 gals
Desired salt concentration: 1.5 lbs/100 gals = 1.88 ppt Current salt concentration = 0.6 ppt
Lbs salt needed = (4400/120) x (1.88 - 0.6) = 36.666 x 1.28 = 46.99 lbs salt
Remember to add gradually, and preferably not into your filter inlet feed. Waterfall or stream is best.
Note: the above formula can be manipulated to give you a fairly accurate figure for pond volume if you know how much salt you added and have salt concentration figures for before and after the addition. 

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