I found this on here, on a thread from 2020. It was @Essjay who referenced the article. You can read the full article here (it takes a while to load) https://web.archive.org/web/20180818083717/http://www.oscarfish.com/fish-food-ingredients.html - I checked with @Essjay if it's okay to post this and we think it is.
What follows below is just a small snipped from the article. These are the bits that interested me the most, especially the discussion about "fish meal". I'll start with the authors own disclaimer. All of the below is a "cut & paste" from the main article I have linked above.
As a disclaimer, I am not a scientist, a biologist, a chemist, or a dietitian. What I am is a hobbyist, an aquarium enthusiast with almost 30 years’ experience with the goal of allowing the fish in my care to live out their life expectancy free of aggression, disease, and environmental or dietary induced ailments. I don't want to be responsible for feeding my fish anything determined by the government as "safe" even though it is banned for human consumption and otherwise labelled by scientific research as even "mildly toxic".
Beware of Proteins
A fish pellet manufactured with poor quality fish meal can be supplemented with high protein grains and by-products resulting in a high protein content listed on the ingredient label. So, you look for those high protein content grains and by-products as a potential warning that a low-quality meal was used. Brewers Dried Yeast (45% protein), Distillers Dried Grains with Solubles (30%), Soy Flour (60%), Wheat Germ (30%) and Soybean Isolate (95%) are some of the most common. An ingredient label with either of these products as one of the first two or three ingredients is suspect.
Something else to consider, all proteins added to a tank via the introduction of food eventually re-manifest as nitrate. If the fish is unable to properly digest the proteins in the food, once passed through the fish, bacteria will. The only winners here are the fish food manufacturer, by taking your money for feeding the bacteria in your tank, and the water company, because you'll still be doing water changes to combat the nitrates resulting from feeding the bacteria. But you and your fish are no better off.
Preferred Protein Sources
Preferred protein sources are those products we would prefer to comprise a majority of the food. The goal is for primary protein sources to originate from aquatic animal or aquatic plant proteins, not from binders and less digestible protein sources (covered later as "non-Preferred protein sources".)
Fish Meal:
Fish Meal is a very generic term that can indicate anything from a quality to a far inferior product. As a general statement, you would prefer to see an ingredient such as "Whole Salmon Meal", which would indicate the inclusion of the entire fish. Absent this, the generic term of "Fish Meal" potentially identifies a dried product primarily manufactured from the leftovers of processed fish after all of the best parts are used for other purposes. Some fish meals are comprised only of bones, scales, skin, blood, and internal organs deemed unsuitable for human consumption.
The above statement requires a little clarity. In the manual that governs (suggests) pet food ingredient labels, the AAFCO definition of fish meal is "the clean, dried, ground tissue of undecomposed whole fish or fish cuttings, either or both, with or without the extraction of part of the oil." There is no AAFCO definition for "Whole Fish Meal", such as "Whole Salmon Meal", so any fish food company that utilizes "Whole Salmon Meal" as an ingredient on their ingredient label is technically out of compliance with AAFCO guidelines. However, AAFCO has not left any mechanism in their guidelines allowing the consuming public to evaluate product quality as, according to their "allowed" definition, "Fish Meal" comprised of 12-month-old scales, skins, bones, blood vessels, and fins would receive the same name on an ingredient label as would fresh whole salmon compiled into a meal. What this means to us, when trying to evaluate an ingredient list, is that an ingredient of "Salmon Meal" may or may not consist of the "Whole Salmon". An ingredient of "Fish Meal" may or may not consist of the "Whole Fish". In essence, there are no properly defined standards by which a determination of quality can be made. So (at least) some fish food manufacturers are filling the void by labelling outside of the defined standard, listing an ingredient such as "Whole Salmon Meal". Since there are some truths in ingredient label laws, if "Whole Salmon" is listed then "whole salmon" must be there, so this can be assumed by us, as the consuming public, to be a superior product over "Fish Meal". If one company does this and gains a market advantage, then everyone does it or loses. So those foods who continue to label as "fish meal" or "salmon meal" are doing so because the "truth in ingredient" laws that do exist prevent them from identifying it as "whole salmon" or "whole fish", because they are using scraps, not the whole fish. This is the approach I when evaluating ingredients of the individual food product reviews.
It is virtually impossible to determine if the fish meal included in your selected food is a quality meal or an inferior product. Some fish meals may be several months to possibly years old before being included in your fish's food and some meals will contain higher quality base ingredients than others. Fresher meals will contain higher levels of nutrients than older fish meals. Fish meal produced from materials that have been allowed to degrade prior to being processed can contain high levels of histamines and can be toxic when consumed over a long period of time. Reputation of the company producing the foods is all you have. Of the research I've conducted, the only generic fish meal for which I have a level of comfort are those fish meals included in Hikari products. Hikari manages product quality from the beginning to end of the process. This is not to say that other companies do not. They very well may, but they are much less forthcoming with information involving the process.
Herring or Salmon Meal (or any other type of "named fish" meal):
Not to be confused with "Whole Salmon Meal" (or other whole fish meal). This is a meal produced from the leftovers (the components deemed unusable for human consumption) of processed salmon (or other named fish). The primary difference between this product and generic fish meal is we know specifically which species of fish the meal is comprised of. Salmon Meal, specifically, contains higher levels of beneficial oils than many other fish used in generic fish meals. Salmon skin is also high in astaxanthin, a colour enhancing carotenoid and powerful antioxidant discussed later in this article.
Whole Salmon (or any other type of Whole "Fish")
When you pull a pellet out of the bag, does it look like a "Whole Fish"?
Marketed as "preferred" over meal products but this is marketing. I would prefer to see a whole fish meal product listed as a primary ingredient.
When evaluating any ingredient list beginning with Whole Salmon (or any other type of whole fish) the first several ingredients should be meat products (either another type of whole fish or a meal product), allowing for increased confidence that meat proteins are indeed the primary component of the food.
Krill Meal
Krill is a preferred ingredient in fish foods. Krill are small shrimp like crustaceans. While Krill may be found in all of the world's oceans, Antarctic Krill is the ingredient we most desire.
Krill, especially Antarctic Krill, is an excellent source of proteins, amino acids, omega 3 oils, and colour enhancing carotenoids. Krill shells are perhaps the best natural source of astaxanthin, a colour enhancing carotenoid and extremely powerful antioxidant.
Krill is only available in its meal (dry) form, so it's location in the ingredient list should be accurate. However, there is a potential defence between "Krill Meal" and "Whole Krill Meal" as Krill tails are sometimes processed for other use.https://web.archive.org/web/20180818083717/https:/support.microsoft.com/en-us/kb/929852
Shrimp Meal
Shrimp meal can be made from either cull shrimp that are being processed before freezing or from whole shrimp that is not of suitable quality for human consumption. The material to be made into shrimp meal is dried (sun or using a dryer) and then ground. Shrimp meal has been used in trout and salmon diets as a source of pigments to impart the desirable colour in the tissues. As a source of protein, shrimp meal is inferior to fish meal. As a source of colour enhancing carotenoids, it is inferior to Krill meal.
Condensed Fish Protein Digest (aka hydrolysed fish protein)
Consists of the condensed enzymatic digest of clean undecomposed whole fish or fish cuttings using the enzyme hydrolysis process. It can better be defined (and is listed on some labels) as fish protein hydrolysate. The hydrolyzation process involves the liquification of whole fish or fish cuttings in a vat of enzymes. The bones and scales are discarded with the subsequent slurry passed through a spray dryer. The end product is a highly digestible protein that is practically void of ash and phosphate.
What do I look for in a Fish Food Ingredients List?
Aquatic Meat Proteins
The preference for a primary ingredient is a named meal protein, preferably a whole "named fish" meal such as Whole Herring Meal or "Whole Krill Meal". Generic fish meals, for the most part, present their own concerns, as detailed a bit later. Use of "Whole Herring Meal" (or other whole named fish meal) indicates two things. First, the use of a meal product as the primary ingredient indicates its weight order, as reflected in the ingredient list, is accurate (listed at its dry weight). Second, use of the word "Whole" suggests the whole fish was used, not just the skin, scales, bones, blood, and other leftovers deemed unsuitable for human consumption, as may be the case with a generic "fish meal",
The industry has almost made it impossible for a normal human to diagnose what is included in pet food by reading an ingredient label.
There is an order of preference as it relates to meat proteins. Krill and Krill meal are the high end of optimum ingredients, following by Whole Herring Meal, followed by most other types of "Whole Fish Meal", with acceptable fish being Salmon, Manhaden, Anchovies, Sardines, etc..., followed by meals in the same order that do not include the word "Whole". Last in preference would be generic fish meal from unknown sources (names of the types of fish are not included).
Plant Proteins
Even carnivores in captivity need plant products in their diet. In the wild, they receive plant nutrition via the gut contents of their prey. In captivity, their prepared foods should compensate for this. At least consider Spirulina listed as a major ingredient a significant bonus. I consider it criteria. Spirulina is digestible and healthy for even the most hardcore carnivore.
Plant products are a natural source of many vitamins and minerals so their inclusion, in sufficient quantities, negates a need for massive supplementation with synthetic vitamins, which are less usable by the fish and sometimes even dangerous.
The same rules applying to meat proteins also apply to plant proteins. When attempting to identify a food for herbivores, the first ingredient should be a plant product in a meal form, such as "Spirulina Meal" or "Kelp Meal". If the first ingredient is "Fish Meal" and then Spirulina or Kelp is listed later in the list as the third, fourth, or later ingredient, then the actual acceptable vegetable content of the food is very low. The food is just a standard fish food marketed as an herbivore/algae flake/pellet/wafer. Preferred plant proteins are actually a minor ingredient.
Multiple Protein Sources
In addition, you don't want a single form of acceptable protein. A quality food will list several forms of animal and plant proteins within the first line of ingredients. A significant majority of protein should come from named aquatic animals (fish, salmon, herring, krill, brine shrimp, plankton, squid) and plants (Spirulina, Kelp, Spinach, Algae, Vegetable Extract) and not from protein add-ons and fillers such as soy, wheat, and corn products, which should (ideally) be limited to no more than 20% of the food, although for herbivores and omnivores (such as Oscars) this can likely be increased to as much as 30%.
Meat Meal
At a minimum, Meat Meal contains parts of animals (mammals) considered inedible as well as diseased and dying animals unsuitable for human consumption. Even more outrageous, it may contain anything from zoo animals, to roadkill, to fetuses, to potentially even euthanized dogs and cats (hidden in the legal paperwork as "condemned animals"). No pet food should contain these ingredients, let alone a fish food that should contain aquatic animal protein, not mammals and poultry.
Poultry Meal
Poultry meal is a dried product manufactured from the leftovers of processed poultry after all of the best parts are used for other purposes. It can be expected to contain some amount of feathers. Digestibility is questionable.
Fish foods should contain aquatic animal proteins, not mammals and poultry.
Non-Preferred Protein Sources and Binders
When judging protein content of fish foods, it is necessary to perform some mental math (although you don't have all of the numbers.) Preferred proteins combined, should out weight all non-preferred proteins combined. So, you must mentally calculate the totality of all of the ingredients listed below as non-preferred protein sources against the totality of the ingredients listed previously as Preferred Protein sources (keeping in mind wet weight vs. dry weight). Of course, anytime the generic term "Fish Meal" is utilized these calculations are further complicated because you have no way of knowing, aside from company reputation, the quality of the meal and its protein content. Nor we do we know the actual percentages of the individual ingredients.
When performing this mental math, what you'll find is that very few available foods actually add up. What we are feeding our fish are binders and non-preferred proteins.
Many of these "non-preferred" ingredients are very high in proteins. At issue is these proteins are largely derived from starches and carbohydrates. The ability of fish to digest these proteins is questionable. Not to mention high starch content brings into play an entirely new discussion of glucose, glycogen, and body weight. Suffice it to say that if you are feeding your fish a diet heavy in the below non-preferred protein sources you are likely making your fish fat, which includes adding fat to the liver. Fatty liver disease is a leading cause of death in captive fish.
Some content of these ingredients is expected, even necessary. But they really should not make up more than about 20% of the food, although for herbivores and true omnivores (such as Oscars) this can likely be increased to as much as 30%.
Brewer's Dried Yeast:
A by-product of the beer making process, this ingredient contains about 45% protein and is rich in Vitamin B. Its use in fish foods is as either as a protein source or a vitamin supplement. Studies do exist identifying its capacity to improve fish growth rates. When used as a supplement comprising between 2% and 4% of the food, this is an acceptable product. When used as a primary provider of protein comprising 25% or more of the food it is less acceptable as protein digestibility concerns have been documented.
Corn Starch
Cornstarch, also sometimes called corn flour, is produced by grinding, washing, and drying the endosperm of the corn until it reaches a fine, powdery state. Corn starch is gluten free. Its use in fish foods is as a binding agent and filler. Digestibility is questionable.
What follows below is just a small snipped from the article. These are the bits that interested me the most, especially the discussion about "fish meal". I'll start with the authors own disclaimer. All of the below is a "cut & paste" from the main article I have linked above.
As a disclaimer, I am not a scientist, a biologist, a chemist, or a dietitian. What I am is a hobbyist, an aquarium enthusiast with almost 30 years’ experience with the goal of allowing the fish in my care to live out their life expectancy free of aggression, disease, and environmental or dietary induced ailments. I don't want to be responsible for feeding my fish anything determined by the government as "safe" even though it is banned for human consumption and otherwise labelled by scientific research as even "mildly toxic".
Beware of Proteins
A fish pellet manufactured with poor quality fish meal can be supplemented with high protein grains and by-products resulting in a high protein content listed on the ingredient label. So, you look for those high protein content grains and by-products as a potential warning that a low-quality meal was used. Brewers Dried Yeast (45% protein), Distillers Dried Grains with Solubles (30%), Soy Flour (60%), Wheat Germ (30%) and Soybean Isolate (95%) are some of the most common. An ingredient label with either of these products as one of the first two or three ingredients is suspect.
Something else to consider, all proteins added to a tank via the introduction of food eventually re-manifest as nitrate. If the fish is unable to properly digest the proteins in the food, once passed through the fish, bacteria will. The only winners here are the fish food manufacturer, by taking your money for feeding the bacteria in your tank, and the water company, because you'll still be doing water changes to combat the nitrates resulting from feeding the bacteria. But you and your fish are no better off.
Preferred Protein Sources
Preferred protein sources are those products we would prefer to comprise a majority of the food. The goal is for primary protein sources to originate from aquatic animal or aquatic plant proteins, not from binders and less digestible protein sources (covered later as "non-Preferred protein sources".)
Fish Meal:
Fish Meal is a very generic term that can indicate anything from a quality to a far inferior product. As a general statement, you would prefer to see an ingredient such as "Whole Salmon Meal", which would indicate the inclusion of the entire fish. Absent this, the generic term of "Fish Meal" potentially identifies a dried product primarily manufactured from the leftovers of processed fish after all of the best parts are used for other purposes. Some fish meals are comprised only of bones, scales, skin, blood, and internal organs deemed unsuitable for human consumption.
The above statement requires a little clarity. In the manual that governs (suggests) pet food ingredient labels, the AAFCO definition of fish meal is "the clean, dried, ground tissue of undecomposed whole fish or fish cuttings, either or both, with or without the extraction of part of the oil." There is no AAFCO definition for "Whole Fish Meal", such as "Whole Salmon Meal", so any fish food company that utilizes "Whole Salmon Meal" as an ingredient on their ingredient label is technically out of compliance with AAFCO guidelines. However, AAFCO has not left any mechanism in their guidelines allowing the consuming public to evaluate product quality as, according to their "allowed" definition, "Fish Meal" comprised of 12-month-old scales, skins, bones, blood vessels, and fins would receive the same name on an ingredient label as would fresh whole salmon compiled into a meal. What this means to us, when trying to evaluate an ingredient list, is that an ingredient of "Salmon Meal" may or may not consist of the "Whole Salmon". An ingredient of "Fish Meal" may or may not consist of the "Whole Fish". In essence, there are no properly defined standards by which a determination of quality can be made. So (at least) some fish food manufacturers are filling the void by labelling outside of the defined standard, listing an ingredient such as "Whole Salmon Meal". Since there are some truths in ingredient label laws, if "Whole Salmon" is listed then "whole salmon" must be there, so this can be assumed by us, as the consuming public, to be a superior product over "Fish Meal". If one company does this and gains a market advantage, then everyone does it or loses. So those foods who continue to label as "fish meal" or "salmon meal" are doing so because the "truth in ingredient" laws that do exist prevent them from identifying it as "whole salmon" or "whole fish", because they are using scraps, not the whole fish. This is the approach I when evaluating ingredients of the individual food product reviews.
It is virtually impossible to determine if the fish meal included in your selected food is a quality meal or an inferior product. Some fish meals may be several months to possibly years old before being included in your fish's food and some meals will contain higher quality base ingredients than others. Fresher meals will contain higher levels of nutrients than older fish meals. Fish meal produced from materials that have been allowed to degrade prior to being processed can contain high levels of histamines and can be toxic when consumed over a long period of time. Reputation of the company producing the foods is all you have. Of the research I've conducted, the only generic fish meal for which I have a level of comfort are those fish meals included in Hikari products. Hikari manages product quality from the beginning to end of the process. This is not to say that other companies do not. They very well may, but they are much less forthcoming with information involving the process.
Herring or Salmon Meal (or any other type of "named fish" meal):
Not to be confused with "Whole Salmon Meal" (or other whole fish meal). This is a meal produced from the leftovers (the components deemed unusable for human consumption) of processed salmon (or other named fish). The primary difference between this product and generic fish meal is we know specifically which species of fish the meal is comprised of. Salmon Meal, specifically, contains higher levels of beneficial oils than many other fish used in generic fish meals. Salmon skin is also high in astaxanthin, a colour enhancing carotenoid and powerful antioxidant discussed later in this article.
Whole Salmon (or any other type of Whole "Fish")
When you pull a pellet out of the bag, does it look like a "Whole Fish"?
Marketed as "preferred" over meal products but this is marketing. I would prefer to see a whole fish meal product listed as a primary ingredient.
When evaluating any ingredient list beginning with Whole Salmon (or any other type of whole fish) the first several ingredients should be meat products (either another type of whole fish or a meal product), allowing for increased confidence that meat proteins are indeed the primary component of the food.
Krill Meal
Krill is a preferred ingredient in fish foods. Krill are small shrimp like crustaceans. While Krill may be found in all of the world's oceans, Antarctic Krill is the ingredient we most desire.
Krill, especially Antarctic Krill, is an excellent source of proteins, amino acids, omega 3 oils, and colour enhancing carotenoids. Krill shells are perhaps the best natural source of astaxanthin, a colour enhancing carotenoid and extremely powerful antioxidant.
Krill is only available in its meal (dry) form, so it's location in the ingredient list should be accurate. However, there is a potential defence between "Krill Meal" and "Whole Krill Meal" as Krill tails are sometimes processed for other use.https://web.archive.org/web/20180818083717/https:/support.microsoft.com/en-us/kb/929852
Shrimp Meal
Shrimp meal can be made from either cull shrimp that are being processed before freezing or from whole shrimp that is not of suitable quality for human consumption. The material to be made into shrimp meal is dried (sun or using a dryer) and then ground. Shrimp meal has been used in trout and salmon diets as a source of pigments to impart the desirable colour in the tissues. As a source of protein, shrimp meal is inferior to fish meal. As a source of colour enhancing carotenoids, it is inferior to Krill meal.
Condensed Fish Protein Digest (aka hydrolysed fish protein)
Consists of the condensed enzymatic digest of clean undecomposed whole fish or fish cuttings using the enzyme hydrolysis process. It can better be defined (and is listed on some labels) as fish protein hydrolysate. The hydrolyzation process involves the liquification of whole fish or fish cuttings in a vat of enzymes. The bones and scales are discarded with the subsequent slurry passed through a spray dryer. The end product is a highly digestible protein that is practically void of ash and phosphate.
What do I look for in a Fish Food Ingredients List?
Aquatic Meat Proteins
The preference for a primary ingredient is a named meal protein, preferably a whole "named fish" meal such as Whole Herring Meal or "Whole Krill Meal". Generic fish meals, for the most part, present their own concerns, as detailed a bit later. Use of "Whole Herring Meal" (or other whole named fish meal) indicates two things. First, the use of a meal product as the primary ingredient indicates its weight order, as reflected in the ingredient list, is accurate (listed at its dry weight). Second, use of the word "Whole" suggests the whole fish was used, not just the skin, scales, bones, blood, and other leftovers deemed unsuitable for human consumption, as may be the case with a generic "fish meal",
The industry has almost made it impossible for a normal human to diagnose what is included in pet food by reading an ingredient label.
There is an order of preference as it relates to meat proteins. Krill and Krill meal are the high end of optimum ingredients, following by Whole Herring Meal, followed by most other types of "Whole Fish Meal", with acceptable fish being Salmon, Manhaden, Anchovies, Sardines, etc..., followed by meals in the same order that do not include the word "Whole". Last in preference would be generic fish meal from unknown sources (names of the types of fish are not included).
Plant Proteins
Even carnivores in captivity need plant products in their diet. In the wild, they receive plant nutrition via the gut contents of their prey. In captivity, their prepared foods should compensate for this. At least consider Spirulina listed as a major ingredient a significant bonus. I consider it criteria. Spirulina is digestible and healthy for even the most hardcore carnivore.
Plant products are a natural source of many vitamins and minerals so their inclusion, in sufficient quantities, negates a need for massive supplementation with synthetic vitamins, which are less usable by the fish and sometimes even dangerous.
The same rules applying to meat proteins also apply to plant proteins. When attempting to identify a food for herbivores, the first ingredient should be a plant product in a meal form, such as "Spirulina Meal" or "Kelp Meal". If the first ingredient is "Fish Meal" and then Spirulina or Kelp is listed later in the list as the third, fourth, or later ingredient, then the actual acceptable vegetable content of the food is very low. The food is just a standard fish food marketed as an herbivore/algae flake/pellet/wafer. Preferred plant proteins are actually a minor ingredient.
Multiple Protein Sources
In addition, you don't want a single form of acceptable protein. A quality food will list several forms of animal and plant proteins within the first line of ingredients. A significant majority of protein should come from named aquatic animals (fish, salmon, herring, krill, brine shrimp, plankton, squid) and plants (Spirulina, Kelp, Spinach, Algae, Vegetable Extract) and not from protein add-ons and fillers such as soy, wheat, and corn products, which should (ideally) be limited to no more than 20% of the food, although for herbivores and omnivores (such as Oscars) this can likely be increased to as much as 30%.
Meat Meal
At a minimum, Meat Meal contains parts of animals (mammals) considered inedible as well as diseased and dying animals unsuitable for human consumption. Even more outrageous, it may contain anything from zoo animals, to roadkill, to fetuses, to potentially even euthanized dogs and cats (hidden in the legal paperwork as "condemned animals"). No pet food should contain these ingredients, let alone a fish food that should contain aquatic animal protein, not mammals and poultry.
Poultry Meal
Poultry meal is a dried product manufactured from the leftovers of processed poultry after all of the best parts are used for other purposes. It can be expected to contain some amount of feathers. Digestibility is questionable.
Fish foods should contain aquatic animal proteins, not mammals and poultry.
Non-Preferred Protein Sources and Binders
When judging protein content of fish foods, it is necessary to perform some mental math (although you don't have all of the numbers.) Preferred proteins combined, should out weight all non-preferred proteins combined. So, you must mentally calculate the totality of all of the ingredients listed below as non-preferred protein sources against the totality of the ingredients listed previously as Preferred Protein sources (keeping in mind wet weight vs. dry weight). Of course, anytime the generic term "Fish Meal" is utilized these calculations are further complicated because you have no way of knowing, aside from company reputation, the quality of the meal and its protein content. Nor we do we know the actual percentages of the individual ingredients.
When performing this mental math, what you'll find is that very few available foods actually add up. What we are feeding our fish are binders and non-preferred proteins.
Many of these "non-preferred" ingredients are very high in proteins. At issue is these proteins are largely derived from starches and carbohydrates. The ability of fish to digest these proteins is questionable. Not to mention high starch content brings into play an entirely new discussion of glucose, glycogen, and body weight. Suffice it to say that if you are feeding your fish a diet heavy in the below non-preferred protein sources you are likely making your fish fat, which includes adding fat to the liver. Fatty liver disease is a leading cause of death in captive fish.
Some content of these ingredients is expected, even necessary. But they really should not make up more than about 20% of the food, although for herbivores and true omnivores (such as Oscars) this can likely be increased to as much as 30%.
Brewer's Dried Yeast:
A by-product of the beer making process, this ingredient contains about 45% protein and is rich in Vitamin B. Its use in fish foods is as either as a protein source or a vitamin supplement. Studies do exist identifying its capacity to improve fish growth rates. When used as a supplement comprising between 2% and 4% of the food, this is an acceptable product. When used as a primary provider of protein comprising 25% or more of the food it is less acceptable as protein digestibility concerns have been documented.
Corn Starch
Cornstarch, also sometimes called corn flour, is produced by grinding, washing, and drying the endosperm of the corn until it reaches a fine, powdery state. Corn starch is gluten free. Its use in fish foods is as a binding agent and filler. Digestibility is questionable.