Trace Elements: The Debate Continues...

[PaPeRo]

To review, there are eight essential trace elements: cobalt, copper, iodine, iron, manganese, molybdenum, selenium, and zinc. How many were you able to name? So it would seem that it would be a good maintenance practice to add these trace elements to your aquarium on a regular basis. Unfortunately, that is not the case. There are several reasons why adding trace elements can be dangerous or just a waste of time and money, or both. First, in order for the trace element to be useful it must get inside the cell, whether that cell is an algae, bacteria, or part of a fish. To get into the cell, the trace element must be in the soluble form. Here lies the first problem--most of the eight elements listed above are not soluble in the aquarium environment due to a] the relatively high redox potential of aquaria, b] the pH of the aquarium water, or c] both a and b. Therefore, adding them in a liquid form to the tank water does not mean they are available for use by the organisms in your tank. In fact, in many cases they will precipitate out of the water and settle to the bottom of your tank--that's the white cloud you see in the water after squirting the mixture in the tank. You can think of them as dollar bills laying on the bottom of your aquarium doing nothing! They can only be re-solubilized if the redox potential drops which can only happen if the oxygen concentration drops to such a low level that everything in your tank dies--not the situation you want to happen in your tank.

So how do organisms get the trace elements they need? For fish and many invertebrates the answer is generally in the food they eat. So if you are primarily concerned with how to keep fish healthy, then feed a varied diet. Most dietary problems with tropical fish seem to be a lack of "greens," i.e., algae. So mix in some Spirulina once in while. A prime example of this is the Lake Malawi Mbuna. They naturally graze on rocks which are covered with algae and small animals, but in many aquaria they are fed a diet consisting of meat protein without the vegetables. This causes dietary problems which leads to poor color and health.

In the more common usage, the phrase trace elements seems to be a catch phrase for anything the writer wishes. I have read articles and bottle labels defining trace elements as including calcium, sodium, magnesium and other things which were not even trace elements but compounds. This is unfortunate as it only serves to confuse the real importance of trace elements. As briefly outlined here, organisms do need certain elements which occur naturally at very low concentrations in many parts of the oceans and lakes of the World. However, to efficiently provide these elements to the organisms in your aquarium takes more thought than just squirting some drops in the water. Further, fish, corals, and plankton are not the same; so don't treat them the same.

Finally, think critically before adding trace elements to your system. What are you trying to accomplish? If it is to improve fish health then soak the feed in a weak solution of the trace elements so they are ingested immediately. If it is for your corals, realize that soft corals are not the same as hard corals and that you need to go slower rather than faster. Don't overdose; this will cause many problems.

©1998, Timothy A. Hovanec, Ph.D.
Originally published in Aquarium Fish Magazine, Jun. 1998

 

[andywg]

Nope, still not peer reviewed scientific paper, so still doesn't answer the question.

Try again

Edit-

And it does not say that the fish do not need trace elements in the water either, and certainly doesn't cover the electrolytes and minerals that also need to be added to RO water.

Edit 2

The article doesn't make any reference to whether the trace elements are more important in marine or FW either, so this post actually covers none of the original points you were so sure on before.

Also, the author appears to be a specialist in the field of filter bacteria colonies, rather than on how fish take up trace elements.

 

[PaPeRo]

Nope, still not peer reviewed scientific paper, so still doesn't answer the question.

Why would I need a peer reviewed paper when you haven't shown any yourself? His credentials certainly BLOW AWAY those of your "armchair experts".

And it does not say that the fish do not need trace elements in the water either, and certainly doesn't cover the electrolytes and minerals that also need to be added to RO water.

Strawman claim since nobody said FW fish don't need trace elements from water. It also doesn't mention electrolytes because it didn't make any claims pertaining to it. YOU were the one to claim they needed to be added to RO water. I'm still waiting for a credible source to support your claim and sorry but "armchair experts" with no degrees are not credible when it comes to biological science.

The article doesn't make any reference to whether the trace elements are more important in marine or FW either, so this post actually covers none of the original points you were so sure on before.

Trace element intake is the same for both humans and fish. It comes from food and/or water. If one can get them from food why would they NEED to get them from water? I guess you didn't get that part of the article where it says you should let the fish ingest the trace elements by dosing food? I guess dosing the water with trace elements is better eh?

Also, the author appears to be a specialist in the field of filter bacteria colonies, rather than on how fish take up trace elements.

Dr. Hovanec earned his Ph.D. in Ecology, Evolution and Marine Biology at the University of California, Santa Barbara.

When it comes to aquatic science, I'll take his word over your "armchair experts" anyday. What kind of psuedo-science does your "armchair experts" specialize in? Osmo-regulation?

 

[andywg]

You are still missing half the argument, it is not just about obtaining the elements, it's about retaining them. You have offered no explanation how the fish are going to overcome the effects of osmosis which will pull the elements out of their body into the pure RO water.

Once you have evidence to show how the fish do that, I may advocate the use of pure RO water without any additions, until that time, I shall continue to point out the proven scientific principle of osmosis and the likely effects thereof.

The above article appears to be talking about the addition of elements (such as calcium) into a marine reef setup, hence the discussion of corals at the end (made more likely by his Ph.D in marine biology). There will already be the elements in the water to an extent from the salt added to RO water to make salt water. replacement will only be for anything that is used. Most of the elements referred to are dosed for coral growth.

It does not in any way touch, or address, the nature of element uptake in FW fish, and the difference between the two types of fish is marked. FW fish have a tendancy to maintain a lower dissolved level of salts and minerals in their body than marine fish.

With regards to the fish taking the elements from the food, there actually appears to be confusion as they appear to take elements from both their food and their environment as pointed out by nmonks:

Looking over one modern fish biology text book I have here ("The Diversity of Fishes", Helfman et al.,1997), it's striking that biologists really don't understand how fish get their minerals and vitamins. Fish seem to take them from their food (as we do) but ALSO from their environment. This could be via their gills or through the water they drink. But we don't know for certain.

Some elements are more readily taken up from the water than food, some more so from the food as detailed in Nutrient Requirements of Fish (1993). It particularly mentions work done by Lall in 1989 showed that

Calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), iron (Fe), zinc (Zn), copper (Cu), and selenium (Se) are generally derived from the water to satisfy part of the nutritional requirements of fish. Phosphates and sulfates, however, are more effectively obtained from feed sources

Taking calcium in particular, a document by the Fisheries and Aquatic Sciences Department, Florida Cooperative Extension Service, Institute of Food Agricultural Sceinces, University of Florida published 12 March 2002 noted that:

Vitamin and mineral requirements of most fish species are not well understood. It is known that fish absorb minerals from the water. Calcium deficiency of channel catfish fry has been associated with calcium concentrations less than 10 mg/L in rearing systems. Calcium chloride has been used to raise the calcium concentration of water used for fry rearing.

The fact that the fish can uptake elements through their gills or water consumed would also imply they can lose them as well via osmosis. As a result of this if the water they are swimming through and drinking in has nothing at all in it (such as RO) then the fish will lose those elements.

 

[andywg]

I dug out a couple of books I have on ichtyology and both indicate that relying on food only for internal solute uptake in FW fish would not be a good idea.

Biology of Fishes, Second Edition by Carl E. Bond states that the osmotic concentration of typical freshwater fish blood is in the range of 265 to 325 mOsm kg-1, marine bony fish maintain a level of around 380 to 470 mOsm kg-1 with Sea water being 800 to 1,200 mOsm kg-1. I am having trouble gaining an osmotic concentration for any freshwater streams, though it appears to be in the region of 1-10 and would expect RO water to be 0.

Fishes: An Introduction to Ichtyology, Fifth Edition by Peter B. Moyle and Joseph J. Cech Jr talks about how freshwater fish operate hyperosmotically and cites the research of Grizzle et al. 1985 which showed that diffusional losses of monovalent ions (e.g., across the gill membranes) are reduced in external environments having higher calcium concnetrations.

This book continues to discuss how lost internal solutes are replaced by those taken in with food or taken up at the gills, noting the work of Laurent et al. 1985 that in especially ion-deficient mountain water chloride cells are well developed on gill lamellae as well as filaments indicating that enough of the necessary internal solutes of freshwater fish are replaced via the gills to require improvemets to that capacity for a fish to succeed in an environment of low solution.

The book then describes the exact method of freshwater osmoregulation based on the beta chloride cells occuring on gill filaments between and occasionally on lamellae (Pisam et al. 1987). Through the reactions at this cells the fish maintain their internal level of sodium and chloride. This same reaction is believed the most probable uptake of calcium by freshwater teleosts.

All of the above shows how freshwater fish depend on some (albeit a comparatively low) level of solutes in the water to effectively osmoregulate. The absence of these solutes by keeping a fish in pure RO water will place unnecessary strain on the fishes' osmoregulation as it constantly tries to combat an increased rate of loss of internal solutes as well as living in water devoid of the natural level of solutes from which it replaced many of them.

 

[CFC]

Papero you are a troll and are trying to cause arguments for your own entertainment while spouting dangerously incorrect advise. Even if fish did not need to have trace elements in the water then using pure R/O water would create a disasterously unstable aquarium enviroment which would suffer greatly fom pH swings as organic acids are released as a bi product of the nitrogen cycle.

For this reason i am suspending your account on a permament basis as it is clear you only want to use the forum to start trouble with other members.

 

[Gnatfish]

Off topic, but out of interest. How will he see your message is he's been suspended?

Back on topic. Would adding trace elements prevent these pH swings or what would you need to add?

Thanks

 

[andywg]

My understanding is it is only the posting that is suspended, not the viewing.

This thread gives some advice on the sort of things required to stabilise RO water. A common thing to do is to cut RO water with tap water so that the stabilising elements are present but at a reduced rate.

 

[CFC]

Using reclaim chemistry products such as KENT R/O right and pH stable add back the minerals which are essential for a healthy stable aquarium but are removed along with the non essential (and possibly bad) minerals and elements by the R/O unit.

The most important of these are calcium sulphate and calcium bicarbonate which provide the buffers that prevent pH crash caused by acids released from decaying matter.

 

[Teelie]

Thank god this dangerously illogical and worthless discussion can finally be dropped. I use R/O water but it's always cut with tap or with re-added minerals like Kent's R/O Right.

 

[pica_nuttalli]

just in case a "new member" suddenly appear to further take up PaPeRo's arguement, i would like to point out that the oft-cited member nmonks is a PhD biologist so not everyone on here is an "armchair" expert.

i'd like to know what sort of professional status PaPeRo has which makes him such a superior authority on the subject of fish. because unless he too has a PhD in biology or similar science, he's just an armchair expert arguing against other armchair experts.

 

[WILDER]

nmonks is a PhD biologist so not everyone on here is an "armchair" expert.

Didn't know that well done nmonks.

 

[voo]

I think Tom Barr (aka plantbrain) has a PhD too

 

[pica_nuttalli]

*bump*