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Nutrition article 8/23/07 Bob, The shorter version of the nutrition article is already published in Fish Magazine International. The "clean" version is attached to this email. No brand name mention, it is strictly a nutritional article. So you are welcome to put it in your website. I'll talk to you soon. Pablo <Thank you my friend... Did see it in FMI... and will gladly place it on WWM, to your credit. BobF>Introduction:
Since humans first began keeping fish in captivity, we have struggled to provide them with optimum aquarium conditions. Meeting the nutritional needs of all species of fishes kept in captivity, considering that they may be herbivores, omnivores, and carnivores has been one of the biggest challenges over the past century of keeping fish.
Fish are an extremely diverse group, and meeting each species nutritional requirements can be very challenging. Hobbyists world-wide have been informed by many so called experts that no single food can meet all nutritional requirements of ornamental fish, with a varied diet being promoted as the best way to ensure that all of your fish's nutritional needs are being met. The reality is that by substituting one nutritionally deficient product for another nutritionallydeficient product, you will not be solving any dietary issues in your fish. It is better to stay with one product that contains all of the variety needed to fulfill all of your fish's nutritional needs.
The last 25 years has seen some major changes in the dog food industry, with numerous brands of super premium dry kibble now being used by millions of dog owners and breeders world-wide. Some of these dry foods are marketed as holistic diets, with certain brands even featuring grain free formulas, containing tonic herbs and botanicals. The higher quality formulas will not only offer complete and balanced nutrition, but most dog owners will feed the same brand exclusively for the entire life of their pet. Dogs today are far healthier, and live far longer than in previous decades, and much of this can be directly attributed to a vastly improved diet.
Yet if you asked the average dog owner, that feeds a single dry food to their dogs, exactly what they feed their fish, most will hold up several containers of tropical fish food, and more than likely will also have some frozen treats tucked away in the freezer.
As Mr. Spock from Star Trek would say: 'This is highly illogical'
Commercial Fish Foods:
Scientific advances throughout the 20th century have allowed keeping fish captive in aquariums easier and more convenient than ever, yet certain segments of the ornamental fish food industry seem to have come to a stand still 30+ years ago, as though there was no room left for improvement. There are currently estimated to be approximately 60 million aquarium hobbyists worldwide, but the subject of fish nutrition seems to be one of the most misunderstood subjects, with all the trimmings of myths and fallacies that have been regurgitated over and over until some of them have almost become regarded as fact. The nutrition supplied to one's fish is the most important aspect of keeping many species alive in captivity, yet it is also the least discussed. This has always struck me as being very unusual.
Aquarists will spend countless thousands of dollars on their aquariums, stands, filters, heaters, fish, etc, yet when it comes to determining what the most optimum diet for their fish is, they seem to either follow the lead of their fellow hobbyists (usually feeding a varied diet), or they choose their food by the images shown on a label. Of course a food with a photo of a Paracanthurus hepatus (Regal Blue Tang) on the label must be designed specifically for that species, correct? Perhaps, but perhaps not.
This subject seems to cause a great amount of confusion, so much so that I felt the need to address it in this article. For the most part the fish food industry is self regulated, basically meaning that it is very easy to manipulate an ingredient list to favour your own product. As an example, if the ash content is quite high in the food, the easiest way for a manufacturer to address that issue is to simply not list the ash content on their label.
Ash can come from bones, shells, and scales of marine animals that are high in calcium and phosphorous, to an extent its presence is simply unavoidable. But, the ash from minerals that come from raw ingredients such as Kelp and Spirulina, though beneficial, should be limited. If an excessive amount is used it can have a negative effect, since fish can only assimilate certain amount much mineral content, and any excess will simply be adding unwanted pollution to the aquarium water.
A manufacturer can also use very little of a common raw ingredient such as spirulina, but use green dye to color the food, and promote it as spirulina food designed for herbivores. If you read the label closely, in some cases you may find that the food that was designed for herbivores, may in fact be based on generic fish meal and contain very little spirulina or vegetable matter, but instead is loaded with fillers such as corn, bran, middling, flour, potato, etc. A manufacturer can list Lobster and Crab in their ingredients to signify quality, but in reality it's nothing but the leftover parts of the animals. A manufacturer can also choose to list many species of fish, one species after another, which gives the illusion that the binding agents (such as middling and flour) are several ingredients down on the ingredient list. The fact is that no matter how many types of fish make up the main ingredient, they are still just part of a single fish meal, period. As an example, if one used 500 lbs. of fish meal per ton of food, it doesn't matter how many species of fishes you use to get that 500 lbs., in the end it's still 500 lbs. of fish meal, and the true second or third ingredient will usually be a binding agent such as flour. Many unaware hobbyists see several kinds of fishes listed at the top of the ingredient list, followed by wheat flour, and assume that this particular brand must have very little wheat flour, and a very high concentration of fish protein. In reality it is no more than a single generic fish meal being used, comprised from numerous species of fish. All fish foods require a high quality binding agent, or they would simply fall apart long before they reached the aquarium. Premium foods use as little as 25% binding agent, while lower quality foods can be as high as 50% of middling and flour. There can also be an extreme range in the utilization of nutrients and overall digestibility within any ingredient category. Shrimp meal is typically comprised of heads and shells, and many fish meals are typically made up from the processing waste of the fish, not the whole fish. Needless to say, a high quality food only uses whole fish, Krill, Mussel, etc, not leftover waste from processing plants.
' The Proof of the Pudding is in the Eating '
Is it possible that one of the main reasons that a varied diet has been promoted for all these years is simply due to the fact that until this past decade most commercial fish foods simply did not provide optimum nutrition? Or politics and profit play some roles in this long held philosophy?
Most magazines and periodicals are geared towards promoting fish keeping, and assisting hobbyists, but because of the need for sponsorship funds from manufacturers to support these types of publications, they simply cannot publish any comparative fish food studies.
Many hobbyists appear to want to see a controlled feed trial study performed on the top commercial foods. These types of studies have been done. In 2002 an in-depth feed trial study on thirty-three of the top fish food brands on the market was performed by a group of highly accredited veterinarians based in Singapore. Again, in Feb 2007 Sparsholt College in United Kingdom has completed a feed trial on lake Malawi cichlids but the results from both of these feed trials will unlikely be made public due to the politics involved. I believe that the true key is for each hobbyist to perform their own feed trials and experiments - as flawed as these experiments may be. It is the only way you will find out and share your findings with other hobbyists to promote the long neglected subject of fish nutrition. Draw your own conclusion, instead of regurgitating what the manufacturers claim. Don't we owe it to our fish to provide them with long-term optimal health?
In 1996 I published the Marine Aquarium Companion, and at that time I considered species such as the Moorish Idol to be 'doomed' when kept in captivity, due to their specialized diet in the wild. At the time that I wrote that book I felt that this species simply could not be kept long term in an aquarium, as no commercial food at that time could sustain some of the more delicate marine species on a long-term basis. What was once considered almost impossible has now become possible. At the time I also considered the Moorish Idol to be a peaceful species, but as I soon discovered every fish is peaceful when they are on their deathbed! A healthy and thriving Moorish Idol is actually quite aggressive, but one will only see this behaviour if the fish is truly thriving, and not just surviving.
Are Most Fish Omnivorous?
To the saltwater fish aquarist, Atlantic Blue Tangs (Acanturus coeruleus) are considered to be primarily herbivorous. Although they are indeed browsers, with lips and dentition designed for snipping off the tips and branches of algae, through feed trial studies we know that they require much more than algae to be maintained in captivity. A study that was performed by Dr. Ruth Francis-Floyd and Chris Tilghman, from the University of Florida, involving captive nutritional management of herbivorous reef fish using Atlantic Blue Tangs (Acanthurus coeruleus) as test subjects and were divided into 3 groups. The first Group was fed washed seaweed (ulva spp.). The second group was fed commercially prepared food designed for herbivores and the third group was fed another commercial diet that was an all purpose diet (marine protein was in the formula). At the end of the study, the first and the second group suffered a high mortality rate, (approximately 80%), with the surviving fish showing clinical signs of malnourishment. Some had become emaciated to paper-thin condition. The third group had only an approximately 30% mortality but the remaining fish has 400% weight gain! While the information from this study was made available during a lecture on November 29, 2001 at the Marine Ornamentals International Conference, held in Lake Buena Vista, Florida, outside of that conference room the results were never made public.
While ichthyologists are busy describing and classifying new species of fish each year, there is much that is still not known about their biology and behavior in the wild.
While most fish do in fact have specialized feeding methods in the wild, and do ingest a certain amount of matter more than others, in the wild almost all fish are opportunistic feeders. Even the more specialized feeders, such as Atlantic Blue Tangs, ingest a certain amount of nutrients from other sources.
In Africa, the fish found in Lake Malawi and Lake Tanganyika are some of the most specialized feeders found on the planet, yet they too are all opportunistic when it comes to feeding. Many people get too caught up in the amount of greens some species eat, vs. where their protein source in the wild truly comes from. The reality is that even though algae dominates the stomach contents of the majority of certain species of African cichlids, and many of these species have indeed been classified as herbivores, the actual foods that make them grow are insect nymphs and larvae, crustaceans, snails, mites, micro-organisms, and zoo plankton, not vegetable matter. This is something that many hobbyists fail to understand.
Some hobbyists may consider feeding Surgeonfish a diet of algae to be more natural than a pellet or flake food, but that couldn't be further from the truth, and the results from the study performed at the University of Florida bear this out.
In the wild, herbivores have to eat constantly for at least 12 hours per day in order to ingest sufficient nutrients. During this period they discharge waste constantly. Under artificial environments, as in an aquarium, they no longer have an unlimited amount of food to graze upon, and even if you could feed them every hour on the hour, it would add massive amounts of pollution to your aquarium. Keep in mind that an aquarium is not even a tiny fraction of a drop in comparison to the volume of water found in an ocean or large lake. In order for aquarium raised fish that are classified as herbivores to thrive, they must take in sufficient nutrients from their diet, and what takes place in the wild, can simply not be duplicated in an aquarium setting.
Carnivores may in fact eat fish in the wild, but those fish will usually be gut-loaded with various smaller life forms, such as zooplankton and phytoplankton. Their prey is part of the natural food chain, and these feeders in the wild provide much more balanced nutrition than frozen silversides found at your local grocery store. Just as captive raised specimens, even carnivores in the wild will consume a certain amount of vegetable matter to acquire various nutrients that their diet may be lacking in. The reality is that carnivores do not just eat meat, anymore than herbivores just eat algae.
Over the years many hobbyists have been led to believe that fish classified as herbivores must eat a diet that's mainly made up from vegetable content in order to truly thrive in captivity, but this is simply not the case. In the past I have failed miserably when using this approach with herbivores, and I have learned from my mistakes.
Protein -- The Building Blocks:
Many hobbyists seem to get hung up on the protein percentages that are shown on fish food labels, without truly understanding exactly what those numbers mean.
The protein percent on a fish food label doesn't really tell you anything about the quality of the protein. The value of protein is directly related to the amino acid content, such as; Arginine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Trytophan, and Valine, which are essentially the building blocks for muscle and growth. The protein percent shown on a label doesn't tell you how that protein was processed, or if it's even in a form that your fish can properly digest and utilize. Unless that protein can be fully digested by your fish, the crude protein percent on a label becomes somewhat meaningless.
High quality protein that is easily digested by fish does not cause gastrointestinal issues, no matter if the fish is classified as herbivorous, omnivorous, or carnivorous. Excess protein is for the most part excreted as waste. The idea of excess protein causing bloat, or any type of gastrointestinal issues in herbivores, is totally inaccurate. Poor quality protein, as well as other hard to digest ingredients can cause bloat etc, but easily digestible protein will never cause any dietary issues. Hobbyists that keep carnivores want the highest protein percentage in a food that they can find, those that keep herbivores seem to want the least, with neither of them understanding the basic principles involved. My advice is to forget about the numbers posted on a label, and concentrate on the quality of the protein.
The ingredients listed on a food label are your first clue as to the quality of the food's protein content. Avoid those that contain too much grain such as wheat middlings, corn, brans, flour, potatoes, or protein derived from Soybean meal. (As indicated by the first ingredients listed; the ingredients that are listed first, are the most prevalent ingredients). Look instead for foods with high-quality, marine-based proteins such as whole Herring, Krill, Mussel, and Squid at the top of their ingredient lists.
Many people think of fish meal as being a poor quality source of protein. This is simply not true. Fish meal is used in a wide variety of animal feed applications including, pet food, poultry, and protein blends. Fish meal is an excellent source of protein and is rich in essential amino acids, fats, and vitamins and minerals. High quality Fish meals such as Herring meal are processed from whole fish, not processing plant by-products.
Certain types of lower quality meals are most likely the cause for Fish meal getting a' bad rap' over the years, and if the Fish meal is comprised of processing plant by-products such as heads, scales, and bones, it will usually result in excessive ash content in the final product. Some fish food labels do not even list the maximum ash content. Obviously it is also much less costly for a manufacturer to use these types of raw ingredients, compared to a high quality source of marine protein such as South Antarctic Krill, Herring, Mussel, or Squid. On the other hand, if the fish meal is not listed in the first ingredient and the ash content is less than 9 %, it usually indicates that too much Soybean, Corn gluten, or Blood meal is being used. While some fish such as Koi can assimilate large amounts of Soybean meal and Corn gluten, most tropical species cannot. Blood meal though high in protein is low in many essential amino acids.
Also keep in mind that a green colored food does not necessarilly contain a large quantity of vegetable matter, anymore than a red colored food equates to Krill being used as the primary ingredient.
Fish do not use carbohydrates very efficiently, and in quality feeds their use is primarily as a binding agent during the manufacturing process. Without some grain the food would simply not hold together. Due to the fact that carbohydrates can be used as a rather inexpensive source of energy in fish foods, some foods utilize a high amount of grains in their formulas to reduce feed costs. The logic is, if it's cheaper, then why not? Grains do have their place in fish foods, serving as binders and to help synthesize lipids and protein. However, if excessive amounts are used, those excess amounts can get stored as fat and will also increase the total amount of undigested solid waste being expelled by the fish. This leads to unwanted pollution being added to your aquarium. Grain by-products are also very difficult to digest by many species, and when used excessively can cause gastrointestinal issues due to poor digestibility and absorption rates. Consequently, pathogenic bacteria start multiplying inside the intestinal tracts, doubling their population as quickly as every 20 minutes, resulting in bloat. In most cases this condition is extremely contagious and the end result is usually fatal.
Lipids -- How Much Is Too Much?
Lipids (fats - omega 3&6) are high-energy nutrients that supply approximately twice the energy as proteins and carbohydrates, and should typically comprise approximately 5-10% of tropical fish diets. They also supply essential fatty acids and serve as transporters for fat-soluble vitamins.
Fatty infiltration of the liver has been designated as being one of the most common metabolic disturbances and frequent cause of death in aquarium fishes. The connection between excessive lipids and fatty liver disease has been common knowledge in the aquaculture industry for many years. The Department of Fisheries and Aquatic Sciences at the University of Florida again recently confirmed this in a study involving African cichlids as test subjects. Yet a recent trend in some fish foods is to use higher levels of lipids in the diet, in order to partially spare protein. Although increasing dietary fat can help reduce the high costs of diets by partially sparing protein in the feed, serious health issues such as excessive fat deposition in the liver are often the end result. In my opinion 5% fat is not enough energy expenditure for any species of fish, therefore in feeds with the aforementioned rate of lipid content the fish will have to tap into the protein source to compensate for some of its energy expenditure. Using this type of formulation, no excess fat is available to be deposited in or around the vital organs such as the liver. Keep in mind that there is a big difference between fat fish, and muscular toned fish.
If cost is an issue, and it usually is, then one needs to take a very close look at the overall feed conversion ratio, which most hobbyists fail to do. It always amazes me when I overhear hobbyists comparing fish foods by nothing more than the sticker price. It's simply impossible to do! In some cases, the food that appears to be more expensive is actually the better buy due to it having much higher digestible ingredients.
Even for the average hobbyist with only one or two aquariums the savings can be substantial between a high quality easily digested food, and one that has fair to poor digestibility. Many hobbyists might not even notice the difference, but when you start running a few thousand gallons worth of tanks, with most of them being bare bottom tanks, the excessive waste build up from one food to the next becomes quite apparent. Also, the cost difference in total food used can be staggering over the course of a single year, let alone a lifetime of feeding your fish.
When a premium high quality food is being used, you just might be surprised at how little food is actually required to keep your fish in optimum health.
Preservatives and Why They Are Necessary
Mentioning the topic of pet food preservatives seems to cause a lengthy debate in almost any pet-keeping circle, especially if the use of ethoxyquin comes up. The whole ethoxyquin scare started from a single rumour, which became so blown out of proportion via internet chat forums that it eventually turned into another urban myth.
The only reason that this preservative ever came into question, was due to a study performed on rats back in 1987 where the dose level of 5,000 ppm ethoxyquin, which is FAR higher than approved levels in pet food, suggested a carcinogenic
potential. Ethoxyquin has since been blamed for a myriad of problems, none of which have ever been proven.
Considering the outcry over this preservative by dog owners worldwide, one would think that by now there would be a plethora of data/studies that actually proved that this preservative caused at least some type of long-term health issue in pets.
There is not a single documented case where ethoxyquin used at approved levels has been found to cause any type of long term negative health condition in a dog, cat, fish, or otherwise. One would think that with all of the hysterical anti-ethoxyquin crusades that have taken place over the past 20 yrs or so that at least one non biased study would be able to prove that this substance can cause serious long term health issues in pets, even when used at appropriate or approved levels. Yet to date, there is not a single shred of scientific evidence that supports such a view.
The fact is that this single preservative has probably saved countless lives of pets from suffering from serious health issues caused by rancid fat. Without preservatives the oil found in fish food would become rancid in very short order. What many hobbyists do not understand is that all fish meal based products will contain ethoxyquin. There is simply no getting around that. The manufacturer may have ethoxyquin listed on their label as a preservative, yet may not even be adding this ingredient at their end.
What most hobbyists fail to understand is that every fish food that uses marine proteins such as krill, fish, shrimp'¦etc. will contain small amount of ethoxyquin, as well as fats into the formula. The United States Coast Guard regulations (Subpart 148.04 -9) requires any vessel entering US waters that contains fish meal, to have the fish meal preserved with ethoxyquin. This is required by law for the safety and health issues that can arise if fish meal is not preserved properly. I personally know of no manufacturer that makes their own in-house fish meal on site, which means that if fish meal is being used in a food, any type of pet food, there will be at least a small amount of ethoxyquin in the final formula. When used accordingly, there is absolutely nothing wrong with using ethoxyquin as a preservative. The FDA approved the use of ethoxyquin as a preservative for both humans and pets, and for decades the maximum amount allowed in pet food was 150 PPM.
In July 1997, after assessing the results of the latest study on ethoxyquin, the FDA's Center for Veterinary Medicine asked that the maximum amount of the preservative be voluntary reduced to 75 parts per million in complete dog foods. The FDA stated that the earlier limit of 150 ppm "may not provide an adequate margin of safety in lactating female dogs and possibly puppies." The reason being that lactating female dogs generally consume far more food (2-3 times) than non lactating females, hence an increased level of every substance in any food will occur. The study showed ethoxyquin levels of 150 ppm had no adverse health effects at maintenance levels, but that by reducing the max amount to 75 ppm it would create an additional safety margin for lactating females and their puppies.
To date, the FDA has found no scientific or medical evidence that ethoxyquin used at approved levels is injurious to the long-term health of humans or animals. Also, the FDA has found no documentation of the claims of harm to any animal. Not even one. Please keep in mind that almost everything and anything can become toxic at high enough levels, including fat-soluble vitamins. No nutritionist would recommend completely eliminating vitamin A, B, D, E and K from the diet just because high levels of these fat-soluble vitamins can be toxic, yet this exact type of logic is what's used when most people discuss preservatives such as ethoxyquin. When used in small amounts to prevent rancidity, preservatives are valuable and important components of the diet.
In the United States the use of male hormones (testosterone) in fish foods is highly illegal, and for good reason. Long-term use of steroids in fish food has been associated with skeletal deformity, increased susceptibility to infections, and pathological changes in the liver, kidney, and digestive tract. Females that are fed sex steroids will 'color up' to the same degree as their male siblings, and juvenile males can become fully colored at a very early age. The downside is that once removed from a diet supplemented with hormones, the females will lose their color, possibly become sterile, and often times the males will also lose much of their color, and never regain it. High quality fish foods contain natural color enhancers that are found in nature, which allow the fish to gain maximum coloration as they mature. The ideal goal for a fish food manufacturer should be to mimic what is found in nature, not a laboratory test tube.
Variety Is The Spice Of Life?
Do fish get bored with one food?
When it comes to this question the majority of hobbyists tend to express in unison
'Variety is the spice of life' or 'Would you want to eat the same food all the time?'
These are all human interjections. In captivity, many marine butterflyfish that only consume coral polyps in the wild, would rather starve to death than switch food. Harlequin Shrimp eat only the feet of the Starfish, Monarch Butterflies only eat milkweed, and Koala Bears only eat Eucalyptus leaves.
As long as the one food can sustain the fish in a thriving condition this should not be an issue. Fish are creatures of habit; they are simply not capable of getting bored.
Can fish thrive on one food? The answer is yes! Fish do require a varied diet, but if that one single food is made from a wide variety of high quality raw ingredients, the varied diet that many hobbyists seek can indeed be found in one single formula. If one was to take all of the various ingredients found in a typical wide variety of formulas, and create a food that contained all of these various ingredients in a proper ratio and balance, would it not be the same as feeding all of these foods separately? If only high quality premium ingredients are being used, in many cases that single food might actually be much better for the fish.
This concept has been proven in commercial aquaculture since its inception, and there is certainly nothing new to feeding fish a complete and balanced diet by using a single food. The aquaculture industry has been doing just that for the past century. What many hobbyists fail to realize is that the aquaculture industry is responsible for the vast majority of the science that all commercial fish food manufacturers use when formulating their various foods for tropical fish.
While the information gleaned from these aquaculture studies is basically sound, the majority of this research involves fish that are being raised for human consumption. With the exception of the color of the flesh of certain species such as salmon, trout and shrimp, the overall coloration and longevity of the animal is not a primary concern. Unlike most tropical species, fish raised for human consumption have a very short life span. In light of this, food that's designed for warm water Tropical fish has to be modified to ensure that a lower amount of lipids is used, high quality marine proteins are used as the main source of protein, and a wide array of natural color enhancing ingredients must also be supplied via the diet such as Krill (Euphausia superba dana), Spirulina algae (Spirulina platensis), natural Astaxanthin (Haematococcus pluvialis)'¦etc.
Flakes vs. Pellets:
Any discussion that involves fish food deserves a brief explanation on these two types of commercially prepared foods. While flakes have been the most popular type of food for the past 50+ years for hobbyists, commercial operations learned a long time ago that pellets are the superior choice for all feeding applications.
Pellets are preferred over flakes due to the fact that they are more nutrient dense, and much more stable in water. For species of fish over 2-3 inches, pellets are clearly the most optimum method of providing nutrition to your fish. Not only can you feed much less on a volume basis, but pellets will also remain stable in the aquarium for an extended period of time.
By their very design, flake foods are paper-thin; absorb water very quickly, and while doing so leach out much of the water-soluble vitamins in a very short period. Some studies suggest that once flakes are added to the aquarium, the majority of water-soluble vitamins (such as vitamin C) are leached out of a flake food within 60-90 seconds.
This information has been common knowledge in the aquaculture circles for several decades, yet some hobbyists seem to be stuck using outdated and less than ideal methods for feeding their aquarium raised fish. Using pellet food for all feed applications is yet another concept that has been proven in commercial aquaculture since its inception.
Spirulina and Vegetable Matter:
In recent years Spirulina algae has been promoted to a point that almost every hobbyist and manufacturer alike have jumped aboard the Spirulina bandwagon. Many hobbyists seem to think that they need to add large amounts of Spirulina into their fish's diet, which is simply not the case. Although Spirulina algae is indeed a high quality raw ingredient, and it does have its place in most feed applications, it is very high in vitamin A and mineral content.
Since vitamin A is a fat-soluble vitamin, excessive amounts can ultimately lead to toxic levels in a fish. While an inclusion rate of 5% to 10% will increase growth rates, with the added bonus of enhancing the color blue, too much of this raw ingredient will simply impart an unnatural color to the fish, and/or cause long term health issues related to vitamin A toxicity. Most decent quality fish foods already contain sufficient spirulina, and feeding more than what is actually required by the fish is counter productive to say the least.
Fibre comes from plant materials, and it should always be kept at a reasonable percentage. Unless bacteria and enzyme actions take place inside the intestinal tract, fish cannot digest cellulose, because they do not secrete cellulose. In some ways you can view fibre as a laxative (especially fiberous Kelp - a primary food source for Abalone & Sea Urchin.), too much will cause diarrhea. This in turn causes nutrient retention time to be shortened and therefore insufficient time for the intestine to absorb needed nutrients. Sometimes too much of a good thing, can be a bad thing.
Live Foods, Frozen Foods, and Beef Heart:
With many species there is always a risk of fry mortality due to the fry not eating within the first few days. This is why many breeders use foods such as baby brine shrimps, micro-worms, etc, to get the fry to start eating. Fry fed with baby brine shrimp have a more uniform growth rate than those fed a commercial dry food, but once they past a certain stage (2 weeks+), a high quality dry food will in many cases out perform live food. Most live foods can also increase the risk of adding unwanted pathogens, disease, and pollutants to ones system, and in the case of Black worms, White worms and Tubifex worms, these foods contain excessive fat that can deposit in and around the vital organs resulting in long term health issues in the fish.
Most commercially prepared frozen foods consist of approximately 80% water, and the very process of freezing causes animals (such as Brine Shrimp) to break the cell membranes due to expansion and contraction. When this food is then thawed, and rinsed, much of the nutrients will leach out from the animal and what is left are mostly shell with very little nutritional value. Having said that, both live and frozen food has its place in the world of fish keeping because the reality is that there are some fish that simply will not eat dry food. In cases such as this hobbyists have no choice but to offer frozen or live food to entice the fish to eat as soon as possible, and hopefully convert the fish to eventually eat a much more nutritionally sound dry food to ensure the overall heath and longevity of the fish.
Beef heart is another popular food that most Discus breeders use with success in growing their fry out fairly rapidly, as well as to condition their breeders for egg production. While this food will work, it might also have accounted for such a short life expectancy of many Discus. Of all the food out there, this food has the most potential for water pollution. Many Discus breeders in Asia change their water 2 to 3 times a day, just to maintain the water quality in their grow out tanks! The reason that Discus can sometimes be much more difficult to accept pelletized food is because most breeders use beef heart to raise their fry, and fish are creatures of habit. With some effort on the part of the fish keeper, even these Discus can be trained to accept a cleaner and more nutritionally balanced dry food.
Do these foods work? Yes, and they have since mankind first started breeding fish, but many of the present day commercial foods were not available 30+ years ago.
Commercial foods have come a long way in recent years, and although supplementing a fishes diet with live or fresh food can add a bit of variety if one truly feels the need, using a high quality commercial food will come much closer to guaranteeing that everything your fish requires for optimum growth, health, and longevity will be available each and every day. While frozen and live foods may work on a short-term basis, for optimum long-term health one should always attempt to get their fish on a high quality commercial food as soon as possible. The greatest objection that I have with feeding frozen or live food in conjunction with dry food, is that due to the palatability of these types of food, in most cases fish will always prefer live/frozen food over dry food, even though over the long haul fish will be much healthier with a complete and balanced dry food.
I always discourage this type of yo-yo feeding to ensure that a fish doesn't choose its taste buds and olfactory senses, over what's more nutritionally sound. Most young children will certainly choose candy and cake over a well-balanced meal, due to nothing more than the sensation of their taste buds.
Feeding fish might seem easy, but it is actually one of the most difficult things to teach. In my 35 years of being in the commercial fish business, I have rarely run across an employee who knows how to feed fish properly. It is necessary to have the sense of awareness not to overfeed or underfeed. In some ways it is as much an art, as it is a science. The first rule of thumb is; when in doubt, underfeed! If necessary you can always rectify the situation later by increasing the feed amount. However, if you overfeed, then eventually you can run into some serious problems.
While most hobbyists usually overfeed their fish, there are also those that underfeed their fish to such an extent that their fish actually look anorexic. Many reef keepers are guilty of this due to phosphate and nitrate concern. If the fish is truly fat, simply withhold food and feed less. If the fish is too thin, simply feed more. A hobbyist should know that they are in control, not the fish. A healthy fish will always beg for food, but if the fish shows no interest in food, chances are you have a big problem. Either they are sick, or in very bad water conditions.
When you feed pellets, the correct size is very important. Large fish can eat small pellets, but if the pellet size is too large for the fish, they will usually spit it back out, or expel a large portion of the pellet into the water column while chewing. The key is to use a pellet size that allows the fish to swallow it whole. If you keep a mixture of fish sizes in the same aquarium, you can mix different sizes of pellets to ensure that all of the fishes receive their fair share.
Another common mistake by some hobbyists is to pre-soak their pellets, in the misguided belief that this will aid in digestion and prevent swelling of the pellets inside the fishes gut. This is nothing more than an urban myth created by those that simply do not understand the amount of enzymes and gastric acids that are released by most fish when they consume food. Those hard pellets turn into soft mush in a very short period of time! If a pellet food causes gastrointestinal issues in a fish, it will usually be due to the use of poorly digestible ingredients, such as excessive amounts of grains & grain by-products, not from the food swelling up inside the fish's stomach. Most importantly, when you pre-soak pellet food, you are allowing nutrients and water soluble vitamins and minerals to leach out into the water.
Other Important Nutrients
In recent years Vitamin C has been discussed extensively while other vitamins that also play a key role in the overall health of aquarium raised fish seem to have been forgotten.
Vitamins such as A, D2, D3, E, K, B6, B12, Thiamine, Riboflavin, Pantothenic acid, Niacin, Biotin, Folate, Choline, Myoinositol, and minerals such as Calcium, Phosphorus, Magnesium, Sodium, Potassium, Chlorine, Iron, Copper, Zinc, Manganese, Selenium, and Iodine, are also all essential elements in a well balanced fish food.
Unfortunately many hobbyists are simply uninformed about the vital role that all of these nutrients play in a fishes diet. Using the mineral copper as an example, many people still do not understand that copper is an essential trace element needed for all living things, including fish. It is a component of numerous enzymes and is essential for their activities. Even natural seawater contains Copper ( some in the form of copper sulfate), yet many hobbyists are still often concerned about its presence in fish food. Interesting facts: in water, at a rate of 0.8 ppm Copper sulfate is toxic to almost all fish, but Copper sulfate present in fish food can be as high as 700-1,000 ppm with the only symptom in some species being growth retardation. Anything below 665 ppm did not cause growth retardation in either Coho Salmon or Rainbow Trout. Copper toxicity via commercial fish foods, where only trace amounts are used, is a non-issue, even in sensitive reef systems.
Garlic is another key ingredient in quality foods, and when the correct inclusion rate is used this single ingredient can play a major role in the long-term health of your fish.
While a manufacturer may use this ingredient to enhance the overall palatability of their food, its main purpose in a high quality food will be for its anti-parasitic properties. I have personally been using garlic in my farm feed for the past 15 years, and while I have never set up a controlled study to chart the exact cause and effects of this single ingredient, I have noticed a drastic drop in disease in my ponds since implementing garlic in all of my feed. Since adding garlic, I have not had a single case of 'Florida Deep Well Disease' (disease caused by pathogenic bacteria Aeromonas sp. and Psuedomonas sp.) in any of my ponds, vats, or aquariums.
Over the years there have been a number of studies involving the use of garlic in fish food and the anecdotal evidence with regards to feeding fish allicin complex (the active ingredient in garlic) to rid them of parasites always appeared to be quite strong. As of 2006 there is now some recent science to back these earlier claims up, with one of the largest in-depth studies to date. In this particular study the inclusion of garlic at a rate of 3% was shown to increase the overall digestibility of protein, carbohydrates, and fat, as well as to lower the total bacteria count within the intestine, muscles, and water column. It was also found to enhance fish tolerance to environmental stress.
In many ways, fish food is like an interweaving basket, remove one strand, and the whole thing can unravel. There is no one single ingredient that has more value than all others, each and every ingredient used to make up a premium fish food is vitally important to your fishes long term health. More and more evidence has proven that many common fish ailments such as lateral line disease in Surgeonfish, hole in the head in Angelfish, and fin erosion in Tangs, are almost always nutritional issues.
What Constitutes a Superior Fish Food?
While there are still many unknowns in the subject of tropical fish nutrition, especially if one takes into account the thousands of various ornamental species that hobbyists keep and breed in captivity, when it comes to commercially prepared diets, in my opinion the best approach is to use a high quality food that satisfies the crude requirements of all species, especially with marine fish. Freshwater fish may only look mediocre on a mediocre diet, but most will survive. Saltwater fish on the other hand must have a nutritionally complete and properly balanced diet; it is a matter of life and death in many of the more demanding species such as Surgeonfish, Angelfish and Butterfly fish.
This is a basic guideline I will suggest as to how to choose a superior fish food:
(A) Palatability: Fish are governed by olfactory senses and to certain extent taste buds. Needless to say, unless the fish is attracted to the food, no matter how nutritionally superior it may be, it will be useless.
(B) Food as energy intake has to surpass energy output i.e.: locomotion, metabolic function, etc, especially in marine fish. Even though they may be eating in an aquarium, they can and often will waste away slowly until they cease to exist. A nutrient packed food will produce substantial growth rate and optimum health.
(C) The type of protein used has to be easily digested and absorbed by herbivores, omnivores and carnivores. As stated earlier, fish do not receive an abundant food source in our miniscule aquarium environments. Whatever food you feed, it must provide ample daily nutritional requirements for the fish to thrive. Superior food generally produces less waste, hence less pollution in your aquarium.
(D) A high quality fish food should be able to bring out the wide spectrum of natural colors in a fish, not just the color red. It should not turn a Yellow Tang or Yellow Labidochromis, orange, which is often caused by excessive use of astaxanthin.
(E) Fat content should ideally be below 10% to avoid fatty liver disease, except in the case of juvenile fish, which require fat as an immediate energy source in order to spare the much-needed protein for building muscle.
(F) Choose a food that can maintain long-term health for years, not months. I have
personally maintained numerous Angelfish, Surgeonfish, Butterfly Fish, etc. for over 10 years, and they show no sign of aging! How long do fish live if their nutritional needs are met? I suspect that in many cases it should be 20+ years. I also suspect that very few hobbyists have kept the aforementioned species of fish alive for such long periods of time. For some people one or two years would be considered a success story! We are not talking about Damsels, Clown fish, Triggerfish, or other species that are rather easy to keep in captivity, but the marine species that are considered ultra delicate by most hobbyists.
(G) Superior food generally produces less waste, hence less pollution in your aquarium. In other words, excess undigested protein, fibre, minerals (ash), will expel through the gills and feces creating phosphate, ammonia, and nitrogen compounds. This is the reason why Kelp, Spirulina, grain and other difficult to digest proteins should keep at a reasonable percentage. Many hobbyists seem to think that they have to add more Kelp, vegetable matter or Spirulina into their fish's diet, unknowingly adding more pollution to their aquarium. Fish simply cannot utilize all the additional mineral (ash) and fibre. A quality food usually contains ample amount of vegetable matter and minerals. Always remember, what goes in has to eventually come out.
Human nature tends to resist change and this new concept might not be widely accepted by the majority of hobbyists, as the concept of feeding a varied diet has been cemented into the conscious and subconscious mind of almost every hobbyist worldwide. Don't be an expert too quickly, as many of the so-called experts are people who simply know so much that they have no room left in their heads to learn anything new. As for myself, I will
always be a bare footed Charlie! There are always new things surfacing on the frontier of fish keeping, so I always keep an open mind to new information and discoveries. To quote David E. Boruchowitz, the editor of Tropical Fish Hobbyist magazine, 'Much of scientific wisdom today began as a heresies of another time" In the end it's really up to aquarists to experiment in their own aquariums, and draw their own conclusions, and I would strongly encourage fish keepers to experiment with even one aquarium, or one fish, and chart the results.
Remember, only dead fish follow the current. Review the facts and think for yourself.
Video of my aquarium... Pablo Tepoot, New Life Enterprises... Spectrum foods 7/25/07 Bob, This is a video link of my aquarium. The narration & video was made 3 years ago, I think you have the DVD, so there is some discrepancy in time line. I am working on a new one to correct the discrepancy. http://stream01.pixelfish.com/newlife/playerHB_vm.php?mediaType=quicktime&browser=Netscape <I see> Thanks for posting the article, I hope it will help to promote better understanding on fish nutrition and save some fish destined to die of malnutrition. Pablo <A worthy thought, goal and achievement. Thank you Pablo. BobF>
New Life Spectrum Food 4/7/2011
Additional recommended Reading
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Royes, J.B., Murie, D.J., Francis-Floyd, R. 2005. Optimum dietary protein level for growth and protein efficiency without hepatocyte changes in juvenile African cichlids, Psuedotropheus socolofi. North American Journal of Aquaculture 67:102-110.
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Jauncey, K. 1982. The effects of varying dietary protein level on the growth, food conversion, protein utilization and body composition of juvenile tilapias (Sarotherodon mossanbicus). Aquaculture, 27: 43-54.
Vinogradov, A. P., 1953. The elementary chemical composition of marine organisms (Efron and Setlow, translators), Yale University Press, New Haven, 463-566.
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De Boeck, G., De Wachter, B., Vlaeminck, A. and Blust, R. (2003). Effect of cortisol treatment and/or sublethal copper exposure on copper uptake and heat shock protein levels in common carp, Cyprinus carpio. Environ. Toxicol. Chem.22,1122 -1126
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