Calcium and Osmoregulation

[Dataguru]

Calcium in the water is important for osmoregulation

Interactions of pH, Carbon Dioxide, Alkalinity and Hardness in Fish Ponds
http://aquanic.org/publicat/usda_rac/efs/srac/464fs.pdf

However, calcium is the most important environmental, divalent salt in fish culture water. The presence of free (ionic), calcium in culture water helps reduce the loss of other salts (e.g., sodium and potassium) from fish body fluids (i.e., blood). Sodium and potassium are the most important salts in fish blood and are critical for normal heart, nerve and muscle function. Research has shown that environmental calcium is also required to re-absorb these lost salts. In low calcium water, fish can lose (leak) substantial quantities of sodium and potassium into the water. Body energy is used to re-absorb the lost salts. For some species (e.g., red drum and striped bass), relatively high concentrations of calcium hardness are required for survival.

UNDERSTANDING WATER HARDNESS
http://www.ca.uky.edu/wkrec/HARDNESS.htm

Calcium has an important role in the biological processes of fish. It is necessary for bone formation, blood clotting and other metabolic reactions. Fish can absorb calcium for these needs directly from the water or food. The presence of free (ionic) calcium at relatively high concentrations in culture water helps reduce the loss of other salts (e.g. sodium and potassium) from fish body fluids (i.e. blood). Sodium and potassium are the most important salts in fish blood and are critical for normal heart, nerve and muscle function. In low calcium water, fish can lose (leak) substantial quantities of these salts into the water. Fish must then use energy supplied by their feed to re-absorb lost salts. That can reduce the energy available for growth and may extend the time necessary to grow fish to market size.

USING SALT TO TRANSPORT LIVE FISH
http://www.ca.uky.edu/wkrec/SaltStressCatfish.htm

Fish and other vertebrates have a unique and common characteristic. The salt content of their blood is almost identical. Vertebrate blood has a salinity of approximately 9 g/l (a 0.9% salt solution) and a pH of 7.4. Approximately 77% of the salt in blood is sodium and chloride. The remainder is made up primarily of bicarbonate, potassium and calcium. Sodium and potassium salts are critical for the normal function of heart, nerve and muscle. An 8 g/l (0.8%) salt solution made with table salt (sodium chloride) would match the sodium content of blood.

Fish blood is brought into close contact (1- or 2-cell separation) with the environment as it flows through the small blood vessels (capillaries) of the gills and skin surface. Salts diffuse from areas of high concentration (blood) to areas of low concentration (fresh water). Therefore, salts (primarily sodium and chloride) are slowly but continuously lost (osmotic leakage) to the environment. The gills and skin are coated with a thin layer of mucus which helps reduce the loss of salts to the surrounding fresh water. Lost salts are replaced by re-absorbing them from the water or during food digestion. Body energy is used to replace salts.

Research has shown calcium hardness helps control leakage of blood salts and is required for their re-absorption. The desired range of calcium hardness is 125-250 mg/l; 250 mg/l calcium hardness equals the calcium concentration in blood.

http://www.hawaii.edu/HIMB/Faculty/grau.html

In fish, osmoregulation typically consumes 25-50% of the total metabolic output, possibly the largest single component.

http://www.ca.uky.edu/wkrec/RedDrumPhysiology.htm

It is generally recognized that sodium, chloride, potassium and calcium are primarily responsible for osmoregulation in fishes, either by exerting osmotic effects (sodium and chloride) or by affecting uptake and excretion (calcium and potassium).

Environmental calcium concentrations also appear to affect a potassium mediated sodium exchange mechanism which is distinct from the passive processes discussed above. Sodium is actively transported against diffusional gradients producing sodium influx in fresh water and efflux in sea water. When environmental calcium is absent or reduced in concentration, the rates of influx or efflux are reduced (Bornancin et al., 1972; Fleming et al., 1974; Eddy, 1975; Isaia and Masoni, 1976; Norton et al., 1977; Pic and Maetz, 1981).

The environment, whether fresh or saltwater, has unique yet different ionic characteristics from the extracellular fluids of teleosts. Most marine waters (35 g/1 TDS) have much higher concentrations of sodium, potassium and calcium at 10685, 396 and 410 mg/1 (Gross, 1977), respectively, than the extracellular fluids of teleosts (e.g. red drum). Conversely, the concentrations of these ions in freshwater (Boyd, 1979) are typically well below those found in the extracellular fluids of teleosts. Therefore, the differences in ionic composition of teleost extracellular fluid and that of the environment generate an ionic gradient across the membranes (semi-permeable) of teleost surface epithelia.

The surface epithelia of gills and body surfaces are protected from direct interaction with the environment by mucous and intercellular junctions. Fish mucous appears to have calcium binding properties (Chartier Baraduc, 1973). Mucous is a glycoprotein and could serve as a calcium chelating agent retarding ion loss from epithelial cells as a charged surface coat or barrier. Intercellular junctions are specialized areas of attachment between epithelial cells preventing the loss of ions and fluids from the interstitial area beneath (Bloom and Fawcett, 1975). It has been postulated that cell membranes and intercellular junctions are dependent on calcium for normal function (Loewenstein, 1966; Guyton, 1971; Bloom and Fawcett, 1975). This dependence may relate to the routes (perhaps pores or channels) of passive and active ion movements (Guyton, 1971; Fromter and Diamond, 1972, Claude and Goodenough, 1973; Sardet et al., 1979; Sardet, 1980; Nonnotte et al., 1982). While some ion loss or gain occurs as a result of leakiness, it is assumed that energy dependent processes can compensate.

Molecules or ions diffuse from areas of high concentration to areas of low concentration until they are equally distributed. This is true for each specific component of any solution. It is of interest for this discussion that sodium, potassium and calcium concentrations in sea water are higher than those of fish extracellular fluid while those of fresh water are lower. In sea water, the tendency is for sodium, potassium and calcium to diffuse into fish extracellular fluid. In fresh water, the reverse would occur. It is assumed that what diffusion does occur, does so through ion pores in epithelial cell membranes and intercellular junctions (gills and body surfaces). Permeability barriers (ion pores and mucous) and energy dependent ion pumps prevent the ionic composition of fish extracellular fluid from equilibrating with that of the environment.

The results of the ion experiments in this dissertation can be related to the ion pore theory as previously described. In low calcium aquatic environments, the ion pores of the surface epithelia would be submaximally saturated with calcium. This would lower the force or kinetic energy necessary to strip calcium from the pore. If environmental calcium were sufficiently low, a rapid and spontaneous flux of sodium (possibly potassium as well) could occur moving from the fluid of highest concentration to the fluid of lowest concentration. Diffusion would be rapid enough that active (energy dependent) uptake or elimination of ions could not compensate. Death would occur as a result of altered circulatory volume and/or disrupted ion metabolism. This is consistent with the results observed in this study as well as the observations of other researchers (as discussed in the introduction).

[Becky]

Nice summary of articles!

Can we get calcium testers? Or just assume a high gh reflects an adequate calcium concentration?

[Dataguru]

Thanks.

That's why goldies can't live in softened, R/O or distilled water that don't contain the hard water minerals.

I think GH is usually a mix of calcium and magnesium to one degree or another. I think there are tests for calcium. You may also be able to find the number for calcium in your city's annual water quality report or by calling their water treatment department.

[Dataguru]

Moved this from another thread...

Here's another thread on it. and another.

I'm not sure I buy the notion that a .3% or a .6% salt dip will "jumpstart" osmoregulation in a dropsied fish. and the people who keep trying to convince me that's the case, don't appear to be able to tell me the physiology behind their assertion.

I'm sure now that adding epsom salt (magnesium sulfate) won't do any good for a dropsied fish.

Increasing calcium should help in that it reduces the effort they have to expend to try and maintain their fluid and solute balance. The thing is... if the kidneys aren't working, I don't think the gills can compensate.

[small zoo]

So is it a good idea to supplement calcium? For my snail tank I put in Kent's liquid calcium at the rate of one drop per gallon tank water daily. (Snails need a lot of calcium for their shells)

Linda and the zoo.

[Dataguru]

That's calcium chloride isn't it?
I think that's what I used to add calcium when Stripe was dropsied.

I think it's essential to raise GH if you have goldies (or snails) and very soft water. How high, I'm not sure yet. GH for goldies should be at least 100ppm from what I've read so far. I don't think that number came from any "hard" data tho (e.g. scientific research).

The benefits of harder water that I'm sure of so far.
-Harder water makes heavy metals less toxic.
-Goldies need calcium for osmoregulation. 250ppm calcium results in the same concentration as in their blood and reduces the energy they need to spend on osmoregulation.
-The chloride protects against nitrIte (and maybe chlorine) poisoning.

I think it may be good to raise calcium levels to 250ppm anytime fish are stressed or sick because of how it helps them maintain osmotic balance. Sick fish tend to take on too much water and lose electrolites. From those references, adding calcium sure sounds like a good idea.

the pond folks apparently use calcium chloride and baking soda quite a bit, because they have to deal with rain which has no minerals to speak of, diluting the GH and KH of their pond water. This makes me think it's safe. They use the calcium chloride because crushed minerals don't dissolve fast enough to compensate and calcium carbonate is less soluable than calcium chloride.

Right now, given what I know so far, if I had very soft water, I'd raise GH up to at least 100ppm with equal parts of calcium chloride and mag sulfate. I think that gets you a 4 to 1 ratio of calcium to magnesium in the water. that ratio is what I generally hear people who are geeky about water recommend. Also, I would add crushed minerals (oyster shell, coral, dolomite, etc) to the filter and let them dissolve. That's mainly because I'm not sure yet about having all that extra chloride in the water routinely.. plus the crushed minerals also get you insurance against a pH crash while also hardening up the water over time as it dissolves.

[yodafatkitty]

Thank you, that was helpful.

I am still at a loss as how to test for Calcium and/or General Hardness of the water.
I've got an API KH & GH test kit. Now, I'm just curious to see what my general GH is in my aquariums.

The directions for HG indicate that the test is completed when the water in the tube , after heaving been shaken, turns from orange to green.

Well, with just one drop, I'm already at green and I have no idea what that means.

You're supposed to be sure to count the number of drops being added because that's what you use via the conversion chart to determine the GH value.

Beau is back in the 55 gal. He is pretty much the same. The MaracynTwo didn't do a thing. The 3% salt didn't really do anything either. Granted, I only did 5 days of treatment, but without showing any signs of improvement I decided to just end it.
Plus, he still seems like his old self! Eating and swimming around like normal.

[Mz RO]

Blimpey stayed dropsied for 90 days eating until the very end. And in 3% salt and 15 GH.

Green on 1 drop would mean a GH of 1 or 17.9 with the conversion. I just go with drops - easier for my brain.

Your calcium is different than mine - i'm not sure chemically how or if it would affect GH - je ne sais pas. I couldn't find out doing a google search.

[Featherless]

Research has shown calcium hardness helps control leakage of blood salts and is required for their re-absorption. The desired range of calcium hardness is 125-250 mg/l; 250 mg/l calcium hardness equals the calcium concentration in blood.

Quite a lot. My tap water is steadily around 15-16 dGH, and typically has 70-80 mg/l Ca. Both measurements (which I got using the Sera Ca++ and GH test kits) are in line with data provided by the water utility - and I think I'm among the ones with the hardest water on this board.

If my calculations are correct, a Calcium reading of 125 ppm equates to a GH of 22 dH or 390+ ppm, assuming a Magnesium content of around 20 ppm.

Let's just hope that data only applies to channel catfish

[Mz RO]

When I used the calcium chloride the API test kits for calcium weren't accurate - even the web/API instruction kit said so GRRRR. This isn't helpful I know but just an FYI.

[Dataguru]

*groan* I'll look at my RO water spreadsheet when I get home.
I think it will calculate how much calcium and magnesium are present for a set amount of cacl2 or mgso4 added to RO water.

[Dataguru]

Magnesium is more soluable than calcium, so I wouldn't doubt it would be higher in your source water.

when I look at the spreadsheet from the water quality guy in OKC, for the hard water lakes
total calcium carbonate hardness/calcium (Ca++ ppm)/magnesium
(mg++ ppm)
290/28/55
257/44/37
238/48/29
so it looks like it varies around here.

for Calcium Chloride Flake (CaCl2 2H2O)
only 27% of the molecule is calcium.
you get approximately a 2.5 increase in hardness for 1 ppl of calcium (ca++) added.

so I think you you multiply your ca++ number by 2.5, you get how much calcium hardness there is in ppm.

[Dataguru]

The effect of calcium on gill potentials and on sodium and chloride fluxes in the goldfish,Carassius auratus
Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Volume 96, Number 2 / June, 1975, 131-142
F. B. Eddy

Summary Measurements of electric potential and of sodium and chloride effluxes were carried out on a freshwater fish, the goldfish Carassius auratus. The potential was affected by a number of inorganic ion species but that with the most significant influence on transepithelial potential was calcium. The potential was about 10 mV negative in the absence of calcium and about 10 mV positive in the presence of 10 mM/l calcium. Sodium and chloride efflux rates were greatly reduced upon the addition of calcium to the medium. The origin of the transepithelial potential is discussed in terms of the relative permeability of the branchial membranes to sodium and chloride and the factors influencing these permeabilities.

I believe that means both sodium and chloride leaving the fish via the gills was reduced with the addition of calcium to the water.

[Dataguru]

just bumping this up and refreshing my memory given the 1 tsp per gallon MgSo4 thread.

250 mg/l calcium hardness equals the calcium concentration in blood, so that should be GH rather than the concentration of ionic calcium.

Old Fred's dropsied. He's still eating and seems alert as per usual. He's been a side layer for a long time now. I'm fixing to clean out the 10 gallon hospital tank and see if I can find my calcium chloride. I think I'll bump GH higher than 250ppm and see how he does. The 1tsp/gallon MgSo4 thread has me wondering if we could safely decrease the amount of water from leaking in to the fish to the point its kidneys could keep up if GH is high enough.

I'm also tempted to try and work out the concentrations of the various ions if we added salt to the mix as well.

[Dataguru]

Just bumped up calcium hardness by 350ppm in Fred's tank.