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Ash in foods.


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Ash is just a fancy name for minerals. Sometimes these minerals are "bio avaiable" other times the minerals are passed through un-used. Ash is a poor way to define minerals as a high or low ash content doesn't tell you if your fish can actually use the minerals or not. A more specific assay of the form the minerals take would be required to tell you if they can be utilised by the fish. This is costly and unnecessary, because the significant health and growth benefits are imparted through other ingredients. Sure mineral deficiency causes deformities and abnormal growth, but worrying about ash content of high quality foods is a non-event if the fundamentals of the food is correct.

From a bunch of reading I have done it seems protien content (and a couple other additives like garlic, yeast and spirulina) are the most important in terms of growth rates. The protein values that pop up a lot in the reading I have done are 45% for fry, 35% juveniles and 25 - 35% for adult fish.

After these ingredients I'd be looking for the plant pigments that make the fish's colour more vibrant. Through reading, just spirulina as an ingredient boosts the appearance of the fish. Other ingredients can't hurt I guess..... look on the label of your leading brands, each will have their own way of delivering colour enhancing charateristics.

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Sure mineral deficiency causes deformities and abnormal growth, but worrying about ash content of high quality foods is a non-event if the fundamentals of the food is correct.

I personally wouldn't consider ash content to be a non-event, and IMO it should be at least somewhat considered when one is comparing various foods. As an example, if an excessive amount of ash is found in a fish formula it can have a negative effect on overall growth, since fish can only assimilate so much mineral content. HIgh ash content in a food can affect the overall digestibility of the food, and feed conversion ratio and those excess minerals will simply be adding unwanted pollution to the aquarium water. While numbers on a label may not mean much to the average hobbyist, if one considers total digestibility in a feed there can be a big difference between 10% ash content, and 20%. Higher numbers can also offer a major clue as to the quality (and cost) of some of the main ingredients in a feed, such as fishmeal. There is a reason as to why wholesale suppliers sell low ash fishmeal at a more premium price, than a fishmeal with high ash content.

Here's what Hagen/Nutrafin has to say about ash content;


Ash in a fish food is the inorganic material that comes mainly from using inexpensive and poor quality fishmeal containing high amounts of fish bones and scales. Ash is composed of essential and nonessential minerals as well as impurities and even toxic elements. Almost all aquarium fish foods on the market today have high levels of ash that may cause a mineral imbalance harmful to fish health and also contributes to pollute water. Compared to other fish foods, NUTRAFIN Max contains the least amount of ash. Low ash content is guaranteed on the label of NUTRAFIN Max. When you buy fish food, check the guaranteed analysis for ash levels on labels, and remind yourself that low ash content means good quality if other aspects are similar.

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Notice I qualified that with "high quality foods". I don't think you can just look at one parameter and say "That food is crap" - It has to be taken in context of the whole product. Percentages are relative, as the content of one component rises, other values drop. Dropping ash by swapping ingredients is a balancing act, too much herring meal and you approach 70% + protien. Adding grain based meals increases carbohydrate content. The food has to be taken as an "on balance" proposition. True, if ash content is too high then other essential ingredients are not at the right levels. But what I was pointing out that there are important health promoting ingredients eg garlic, spirulina, yeast that deserve the same attention "ash content" is getting in the discussion.

Articles about spirulina in diet.



Effect of feeding Spirulina platensis on growth and carcass composition of hybrid red tilapia (Oreochromis mossambicus × O. niloticus)


Articles about yeast in diet.

Influence of dietary commercial Beaker's yeast, Saccharomyces cerevisae on growth performance, survival and immunostimulation of Oreochromis niloticus challenged with Aeromonas hydrophila.


Also a direct comparison of percentage contents of foods across classes of food. ie wet - semi-moist-dry. Let's take a sardine, measure percentages of protien,ash etc from fresh, semi-moist,and dry sardines. As moisture content drops, the ash and protein levels increase. Lets suppose that a fish's natural diet is almost exclusively sardines. No matter what form that sardine takes 1 whole, or 1 semi moist sardine or 1 pellet (assuming no losses in the process) they get the same nutrients.

Lets look at some scenarios - And I am considering mbuna here as it is what I keep.

Ash could be based with a cerial meal which can contain high carbohydrates. - It is well established that high carbohydrates are bad for fish.

Ash could be relaced with oils - oils at too high a rate cause liver damage to mbuna (the reference escapes me now but I can put it up later)

We can replace ash with protien (different quality fish meals) - ash goes down but protein goes up. Protien above about 45% is wasted when growing fry, above about 30% and it is wasted protein when maintaining adult fish. Again the whole food must be critically analysed, not just one parameter.

In the following study they suggest the best performance for Tilapia (the closest to mbuna I can get info on right now) is at protien levels of 30%.

Effect of protein level and stocking density on growth performance, feed utilization and resistance of Nile tilapia (Oreochromis niloticus) to infection against aeromonas septicemia (Aeromonas hydrophila)

In this study they replace a base-line protein with "high quality" herring meal. It seems not the source of the protein, rather that the correct proteins are present is the most important factor.

"It is concluded that the incorporation level of herring meal into

the reference diet does not affect the proteinADCvalues in juvenile

haddock diets and that the two commonly used equations for

calculating protein ADC result in the same values for highly digestible

feed ingredients like herring meal."

Effect of Dietary Levels of Herring Meal on Apparent Protein Digestibility by Juvenile Haddock, Melanogrammus aeglefinus L.


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TILAPIA (Oreochromis niloticus)


Effects of Garlic (Allium sativum) on Some Antioxidant Activities in Tilapia Nilotica (Oreochromis niloticus)


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I think if you re-read my response, you'll find that in no way did I state that one could look at a single parameter & say "That food is crap". I also noted your use of "high quality foods", but quite frankly have no idea as to what your definition of high quality is.

I stated; I personally wouldn't consider ash content to be a non-event, and IMO it should be at least somewhat considered when one is comparing various foods. Fair enough?

Seeing as the title of this discussion is "Ash in foods", I have no idea what all of the various other links that you posted were attempting to prove, other than ash content is only one of many things that one should compare when looking at a fish food label. I assumed that was a given. I've read all of those studies, and a few hundred more just like them. Of course there are other important factors involved in a high quality fish food, but that doesn't equate to the excess mineral content that makes up the total ash % simply becoming a non-event, such as what you initially stated, no matter how high quality you may personally view the food as being.

You can slice it & dice it in as many ways as you like, when I see ash content in the 20% range, I see excess minerals that are adding no value to the food (which lowers the total digestibility of the product), and ultimately ends up as unwanted pollution in ones aquarium water.

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I re-read what I wrote above. To clarify.

Lets suppose I identify that a particular species of fish eats zooplankton, larval crustacean's etc. I decide to manufature a fish food for that species. I go out and find a source of zooplankton as the basis of the food. Now I supplement it with fish meal if required, garlic, spirulina and yeast, HUFA Omega 3 & 6 in the correct ratios. I formulate it to be 30% protein. Due to the zooplankton content there will be a high ash content as the dried zooplankton is mostly shell. It is high ash, but the ash is not the mineral in ionic form (ie its not like getting a bunch of carbonate salts and adding it to the food "as is") it is all bound up in the chitinous exoskeleton of the zooplankon. (An animal source of fibre, if you will)

Now suppose that I find that the source of zooplankton has run out or becomes prohibitivley expensive. Now I find a different source of proteins, now I use a blend of herring meal, algea, and soybean proteins to achieve 30% protein. I add all the other supplements etc. This time the ash content is low!

In both cases there is undigestable material. In case 1 it is ash, in case 2 it is plant fibre. Both go through unused. Both provide identical nutrient profiles, vitamins, HUFAs, protein, garlic and yeast.

I used to think that "filler" was bad as it provided nothing for the money I pay. However, to achieve 30% protein and low carbs there is another 70% of bulk to fill.

Of course brands with low ash will rubbish other brands that have high ash.That is called marketing. Publications by companies are biased at best and spurious on occasion.

But I can equally see the potential for a brand with aquatic ingredients to start making claims about terrestrial based plants being used. For example, that soy bean meal or corn meal contains high amounts of undigestable fibre that the fish would not naturally encounter.

But just I don't buy claims about ash being "bad". If the ash were from mineral salts, then I'd be worried.

All the other links are so that everybody can read the benefit of other ingredients of fish food. Yeast and spirulina are not things I have heard often discussed in the discussion of foods. Garlic is discussed, but as a food it isn't so much anti-parasitic, it is anti-bacterial and immunity booster, splitting hairs I know, but hey.

And that swapping "average quality protein" for "high quality herring meal" is not the be-all and end-all of fish food.

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And I forgot to say, that for my fish, protein levels of 44% (Nutrafin Max) will not provide any additional benefit to my fish over protein levels of 30% so reducing protein levels will increase either ash or fibre (or worse still carbohydrate) content dependent on the source of protein.

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I mean no disrespect, but this is not a subject that one can simply google up a few studies & then suddenly have a clear understanding of how all of this applies to formulating fish feed.

Due to the zooplankton content there will be a high ash content as the dried zooplankton is mostly shell.

That would be true if one was using processing plant waste, such as most Shrimp meal, as it only consists of heads & shells, sans the meat.

Using your example of zooplankton, a protein source such as Antarctic Krill (Euphausia superba) as a finished meal has a lower ash content than some fishmeals, such as Menhaden meal, and Whitefish meal. Give or take a few % in either direction, Whitefish meal typically has an ash content of 20+%, Krill meal on the other hand has an ash content of only 13%. If one was only shooting for a max of 30% crude protein, and using Krill meal as the main source of protein the final ash content after adding the rest of the raw ingredients would certainly not be in the "high" range. All other things being equal (med-low carb content, etc-etc) the final ash content would probably be around the 10% mark. BTW - chitin only makes up approx 2% of that particular zooplankton meal.

Now if one was to push that protein level up to the 45-50% range, using Whitefish meal as the main protein source, suddenly you are looking at an ash content in the 20% range. Unless of course one is utilizing a lot of starch, as that can & will push the ash content back down.

Whether or not you buy the "claims" of ash being bad is besides the point, excessive ash has always been considered a negative in aquaculture feed for as far back as the science goes. Also, in all the years that I have been in this hobby I can't recall a single "high ash" food ever being referred to as being "high quality". Excessive ash has proven to have a negative effect on the growth of various species of fish, as well as having a negative effect on water quality in a closed system. Most experts agree that in fish food ash should be maintained at levels below 12% due to the fact that digestibility of protein in fish fed low ash diets is generally significantly higher than in fish fed high ash diets.

And that swapping "average quality protein" for "high quality herring meal" is the be-all and end-all of fish food.

Not too sure what you meant by that? While a high quality low ash Herring meal may not be the be-all or end-all, it is most defintely one of the best (and most expensive) sources of protein available in commercial aquaculture feed. It has the highest protein content of all the fish meals, the best amino acid profile, and on average 10% ash content, vs 20% found in processing plant waste such as Whitefish meal.

BTW - in most feed trials the fish are fed twice a day to satiation, which is not something that the average hobbyist ever does, or should typically ever do once a fish begins to reach maturity. If you want to control the total dietary amount of protein you can still feed a nutrient dense food with somewhat higher protein levels, simply feed less.

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I do get what you are saying. And as a general rule I'd agree. But after a lot of reading I got to thinking that there is a lot more food than just one measurement. I said what I said to create discussion. But I'm not taking the p155 (the language filter makes what I typed sound lame) or trying to be disrespectful in anyway. I do appreciate the conversation.

I had a typo with what you quoted, but it was fixed moments after post. I apologise for that, should have proof read. And it confused the issue.

What I meant was it is the balance of the protien that is important. The requirements of fish are best suited by using a fish meal because it has the amino acid mix required. Now if that protien is made from 'fish meal' or 'herring meal' or a blend that matches the protien requirements of fish and is at 30% it seems that growth performance of fish is the same.

Also, I would agree that if only fish frames were used and the protein was boosted by soy, that would not be ideal. Particularly if the food was high temp. heat treated.

But I am hazzarding a guess that heat treated 'ash' from fish meal and non heat treated 'ash' behave in different ways in the digestive system. And that is what I was originally referring to in the opening post. 'All ash isn't created equal'. Some will be roughage, some bio-available in a

I also notice that the krill seemes to go through some sort of processing before addition to fish foods? Is that to reduce the ash content or turn more of the roughage into digestable protien?

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No disrespect taken. I am reading and critically analysing the information presented. Not simply googling and regurgitating.

My background is in biology and chemistry, particularly organic and natural product chemistry. I know the subject has a yawn factor to those who just want to feed their fish. But I find this whole area very interesting. Rightly or wrongly I'm drawing some parallels between tilapia and mbuna. And I am finding it really interesting the number of studies that are trying to find ways to get the same growth performance from the fish while reducing the cost (quality?) of the food.

In my situation, I'm interested in growth of fry. And agree entirely with what you say about fish approaching maturity. There is another entire discussion there .... But I'm keeping that to myself... The entire forum will be catching up on lost sleep, there!

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Perhaps we should have kept this conversation private, so as not to bore anyone that has apparently been forced to read any of this? :)

And I am finding it really interesting the number of studies that are trying to find ways to get the same growth performance from the fish while reducing the cost (quality?) of the food.

In commercial fisheries (salmon, trout, catfish, tilapia, etc) the goal has always been to find a way to do things cheaper. Unfortunately the only real goal in commercial aquaculture is to get the fastest gains in growth, in as little time as possible, and do all of this as cheaply as possible. I would like to believe that most hobbyists do not share this way of thinking, and that overall health & longevity of the fish is the ultimate goal.

The nutritional value of a protein relates directly to its amino acid composition and digestibility.

In this regards not all "fish meals" are created equally, and the various nutrient values will vary, as will digestibility. You have to keep in mind that crude protein values on a fish food label are nothing more than a nitrogen reading taken in a lab, and that crude protein value does not guarantee anything beyond that nitrogen reading. So no, the growth performance will not necessarily be equal, even if the crude protein values stated are exactly the same.

And yes, you are correct in that not all ash is created equally either. In fish meal ash is mostly comprised of calcium & phosphorus, and is highly bio-available to fish. Having said that, there is a limit as to how much of those elements a fish can fully assimilate & utilize. If a manufacturer is utilizing by-product leftovers, with high ash content as their main source of protein, digestibility will suffer. This is what I was referring to previously. Some ash content is unavoidable, and in some cases it is indeed a non-issue. It's not like calcium & phosphorus are a dietary negative, unless there is too much for the fish to utilze. It doesn't really matter what that source of ash is, too much is too much, no matter the source.

Krill is processed for the same reason that most other raw ingredients such as fish meal are. It has a high fat content and is highly perishable raw ingredient that requires immediate processing for proper safety, and storage. This process typically begins on the fishing vessels themselves (most which are very high tech these days), and is later finished after being transported to shore.


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Again thanks for your input.

I am all for getting the best colour and long term health outcomes for my fish. So I don't intent to use food that is high in carbs, that use chromium oxide to help the fish utilise it better, etc. Or other "short cut" methods to quickly produce biomass.

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Sooo....>12% ash = bad. <12% ash = good

good conversation guys, I didn't read all the links, but I also didn't fall asleep.

But then can you belive the advertised ash content on a bottle for fish food anyway as there are no controls as to the information's honesty. Long term established foods have probably been proven over time, but I imagine the constant new brands that come on to the market, with all sorts of wonderful claims would have to be viewed with some doubt?

Didn't understand Duck's comment at all thought I've gotta say.

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I just saw lots of claims about "we have the lowest ash" much like the described example.

I did some calculations and krill fed raw would be 3% ash and dried 13.5% ash due to the water content. That was the real reason I posted in the first place. And it is always good to hear lots of points of view and see more info about foods presented. I know we all want to keep our fish healthy and long lived.

The studies about, garlic, spirulina and yeast.... I got to wondering that they could add almost any "better" ingredient into the the baseline food and get healthier fish. LOL Not doubting that those ingrediants help to boost the fishes health, but those "baseline" foods look crap.

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But then can you belive the advertised ash content on a bottle for fish food anyway as there are no controls as to the information's honesty.

In the USA each state has their own regulatory body that does indeed check for values printed on pet food labels, including fish food. So if someone is fibbing even a wee bit on any printed values (protein, ash, etc), they will eventually be caught with their pants down, and taken to task.

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Yes, and no. Ash content is generally not required by AAFCO and other regulatory bodies, and sometimes when it comes to what's placed on a label, less = more.

Most people have no idea what type of red tape, regulations, and inspections are involved when actually manufacturing pet food, it can be an absolute nightmare for a US based company that has to not only deal with federal regulations, but also each state individually.

In the USA this involves not only the FDA, but also the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS), Veterinary Services (VS), and AAFCO.

In many cases these regulations change on a frequent basis. It's gotten to the point that probably the less info one places on their label, the better, or you'll be updating your labels every 6 months. These changes cost $, for larger companies lots of $$$$ , and someone has to eat the cost of outdated labels, and yet another run of new updated labels.

As an example, some countries may allow Vitamin C to be listed on a pet food label, but all it takes is one overly anal state inspector to decide that it must be listed as ascorbic acid, and you are forced to either remove that listing from your label, or play by their new rules. Even if the vitamin C you are listing is the total content, most comprised from the raw ingredients themselves, not from some vitamin premix. One wrong word or term can equate to your product being disallowed in an entire state, and each state requires a permit just to get your product across their border, and like everything else, you have to pay for that privilege.

And that's just what takes place within the USA, now factor in all of the other various countries that some fish food products are exported to & things can become goofy stupid.

The USA & Canada couldn't give a rats behind with regards to things such as GMO products, but the UK requires additional labeling if the product contains .9% or greater GMO. A country such as Turkey doesn't allow any GMO products, not even if it's as little as .0001%. They use outdated testing equipment that simply tests positive, or negative, and if it's positive your shipment will be refused at their border. Go figure?

I seriously doubt that fish food will ever come under the same type of scrutiny as dog/cat food, but it doesn't get any free passes either. Having said all that the way things currently are there are a number of ways that one can bend the rules & manipulate a fish food label, and some manufacturers do take advantage of these loop holes.

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Sooo....>12% ash = bad. <12% ash = good

good conversation guys, I didn't read all the links, but I also didn't fall asleep.

But then can you belive the advertised ash content on a bottle for fish food anyway as there are no controls as to the information's honesty. Long term established foods have probably been proven over time, but I imagine the constant new brands that come on to the market, with all sorts of wonderful claims would have to be viewed with some doubt?

Didn't understand Duck's comment at all thought I've gotta say.

See, what I got from this was, there is no definitive number you can put out there as a good/bad line on a single component of foods.

Also, that 'ash' in itself seems to be basically a bs component anyway. (Can be used to group whatever leftover minerals the manufacturer feels like including in the 'ash' component count.)

The (yawn) reaction came from the fact that the posts seemed to get longer and longer, as a way for people to repeat what they'd already said.

When I did debating, repeating yourself ad infinitum without introducing new evidence or new information, was a loss.

Making potentially interesting or educational discussions harder to follow by making the posts prohibitively long, without actually introducing any new facts or evidence = (yawn)

I take it nobody shares my sense of humour. Or maybe that anyone who does, was already asleep by post 6.

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But the difference here is that we are not competition debating. Merely ensuring that correct info in the correct context was conveyed. I don't think either RD or myself was trying to 'win' just present some facts as they apply in different situations.

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