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Thread: Different Forms of Marine Fish Foods

  1. #1
    Brittle Starfish

    Join Date
    May 2006
    So CA
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    Different Forms of Marine Fish Foods



    I have posted a few times a statement such as, "The least desirable marine fish food is flake and/or pellets." That does not mean these fish food forms are bad. Just that they are the least desirable in the list of the different food forms available to our marine fish.

    There are several different forms of marine fish food we have to choose from, to feed our fishes. Each has at least one positive attribute and each has at least one negative attribute. There is a down and upside to every form of fish food we have available to us. The question is, When does the downside outweigh the upside? Part of that question has to take into account what is in the best interest of the fish. The aquarist wants to give their fish the best edge they can to thrive a captive life.

    The best ingredients for marine fish food has been covered here: Fish Health Through Proper Nutrition. Here I'm talking about the form the proper foods come in.

    I have listed the different forms our marine fish food comes in, in the order from first preferred to least preferred, and provide some upsides and downsides to each.


    1. Live. This can be harvested from sea water, found at some local fish stores, or home raised/grown.

    2. Frozen. This can be found in prepared foods for purchase or it can be gathered from a seafood store and prepared at home for feeding.

    3. Gelled Frozen. This can be found in prepared foods for purchase or it can be the form to make home made food recipes.

    4. Freeze Dried. This food can be bought at fish stores. It is prepared by removing water from the product while under reduce pressure. In this preparation, water and volatile organics are removed from the product. However, there are different processes which can remove more nutrients.

    5. Flake. This food can be bought at fish stores. It is prepared by processing foods, drying it out in thin sheets and then chopping it into different sizes.

    6. Pellets, Sticks, Discs, etc. This food can be bought at fish stores. It is usually a mix of foods that is bound together by a land product, usually wheat or wheat gluten.


    This is not an exhaustive listing of the pros and cons of each type of food form, but it should capture the highlights.

    1. Live.
    Downside. Live food runs the risk of bringing disease into the marine system. Since only marine foods should be used, then there is a real risk of disease getting into the marine system from this form of food. How risky? Probably very little. The risk can be totally avoided by raising the live food at home or under controlled conditions. Another way is to quarantine the live food to verify it does not contain pathogens harmful to the marine fishes. A single live food is usually not good enough to provide all the nutrients the fish needs. That is, the fish will need a variety or diversity of live food that has itself been nourished on a variety of different nutrients. Sometimes the size of these foods prevents the fish from eating it: too large and the fish cannot swallow it; too small and the fish might not see it.

    Upside. This food is totally natural. The fish recognizes it. The food contains nutritional ingredients needed by the marine fish. The food has not "spoiled" (begun to decompose) and does not bring with it harmful bacteria of the kind that live off spoilage. Some live foods can be gut loaded with other nutrients to improve the nutrient value of the food.

    2. Frozen.
    Downside. Frozen foods can be deceiving in the sense that the food is not whole. Shrimp tails, although a fine source of smell, taste, and protein, is not the whole organism. Our marine fishes need the whole organism to be nutritionally satisfied. Human frozen foods sometimes contains preservatives. Packaged frozen foods may bring with them bacterial and microbial pathogens. The freezing process can rupture the cell wall of the food, on a microscopic level. This releases the nutrients into a juice around the frozen mass. This liquid just feeds the micro organisms and algae in the marine system and does not get to the fish. On a larger scale, the aquarist might see that the frozen food does not look whole, but comes in bits. Like frozen mysis that doesn’t even look like mysis should when put into the aquarium at feeding time. This food needs rinsing off to remove the juice. Large chunks will need to be chopped or cut to fit the mouths of the fishes. As in all prepared foods, there is a risk that the mix of frozen food doesn’t contain the right kinds of ingredients.

    Upside. Frozen foods provides the next-best nutritional value to live marine fish food, if they were chosen properly (whole sea life forms) and frozen in a way to keep the organism whole. They are easy to find to buy. Frozen foods are relatively easy to feed. Some of these foods can be bought raw by the aquarist at sea food stores for home preparation. Additionally, freezing a sea food will kill most larger parasites, flukes, worms, etc. (but not all pathogenic bacteria).

    3. Gelled Frozen.
    Downside. The gelled food bought prepared can be much more expensive than it needs to be. Prepared gelled foods can encapsulate pathogens and send these directly into the digestive track of the marine fish. Feeding it can be a bit of challenge. It needs to be chopped or cut into sizes suitable for the mouths of the fishes being fed.

    Upside. This form has the best advantage for encapsulating all nutrients the sea food has to offer. It does not matter if the freezing has ruptured the cells, since it all should be trapped in the gelatin. All sorts of sea foods can be used for the recipe. Included into the recipe can be vitamins and supplements that are trapped in the gel and not washed away. If home made, the aquarist knows exactly what went into it. When prepared properly, can be a single, staple diet for marine fishes. That is, a variety of food isn’t needed.

    4. Freeze Dried.
    Downside. Freeze dried sea life contains salt. These salty foods are not good foods for freshwater fishes. So some processes remove the salt from the food during freeze drying. This makes the food suitable for freshwater fishes, but it also removes nutrients needed by the marine fishes. This process does not kill all harmful bacteria. The freeze dried food is fragile and easily broken into bits. This creates a lot of dust and pieces during the handling of them. These bits do not have to have the same nutritional value as the whole piece and sometimes is a cheap filler, and of lower than desired nutritional value to the marine fish. Not a good way of increasing nutrient value by adding supplements. Is usually more expensive that most other forms when compared by (e.g., protein) weight.

    UpsideAn excellent means of capturing the nutrients without all the water. All higher forms of parasites like worms, flukes, etc. are killed in the process. The process may also kill many of the harmful bacteria. Prefer only those that are dried without removing salt, for marine fish. The aquarist can take the dry food and soak it in their own vitamin and fat supplements. The freeze dried food will retain some of this until eaten.

    5. Flake
    Downside. This is a severely processed food. The processing looses some nutrient value. If using heat, the process can damage proteins and other ingredients. Many preparation contain foods not advantageous to marine fishes and with wheat and/or wheat gluten, has the same downsides as 6. below. Some contain foods that the marine fish does NOT digest so becomes a pollutant when the fish excretes the undigested parts. Some liquids vitamins loose their potency when processed into this form. Low grade foods are often used in these preparations. It has no form that the wild marine fish recognizes as its proper food. Not a good enough nutritious food to be a staple diet. When opened it begins to take on moisture and thus begins to decompose/age with the bacteria that contaminate the flakes.

    Upside. This form has the advantage of encapsulating many ingredients that are not dispersed in the tank. This reduces pollution. The aquarist can take the dry food and soak it in their own vitamin and fat supplements. The flake food will retain some of this until eaten.
    Easy to feed. Usually inexpensive.

    6. Pellets, Sticks, Discs, etc..
    Downside. The binder used for these forms of fish food is wheat, gluten, or other land products. These products cannot be digested by marine fishes. They are excreted by the fish and pollute the aquarium. In addition, these kinds of products mislead the buyer as to what is the true usable content of the food. For example, since wheat contains protein, the total protein of the product is given on the package, but not all that protein can be used by the fish, so the protein content on the package is misleading as to what is the ‘usable’ protein. The ingredients of these foods are usually the furthest from the desired ingredients for feeding marine fishes. As with flakes, this process can alter the nutrient value of the food. Some liquid supplements cannot retain their value in this process. I strongly urge all hobbyists and aquarist to NOT FEED PELLET FOODS on any kind of regular basis.

    Upside. This method encapsulates the food. When dry, it reduces tank pollution when put into the tank in the sense that more goes into the fish than into the water at feeding time, even though the fish can't digest it all properly, it still ends up loose in the marine system. The aquarist can take the dry food and soak it in their own vitamin and fat supplements, it easily absorbs other liquids. The pellet food will retain some of this until eaten. These foods come in a wide variety of sizes to fit the mouth of the fish. Very easy to feed.


    When the upsides and downsides are weighed against each other, it should be clear that the order of preference is as I have listed them. This does not mean the ones down the lower end of the list are unacceptable. It just means they are not suitable for an ongoing diet choice. I use all these forms to feed my marine fishes. I use pellets once every month.

    I feed live foods one a month. I prepare my own frozen foods from sea foods (e.g., clams). I buy prepared gelled foods, but mostly I just use my own gel formula. I feed flakes and pellets about 1% of the feedings, but no more. It is just so easy when I am in a hurry and forgot to defrost something (we've been there even in feeding our families).

    If the reader endeavors to keep to the top half of the list for the bulk of feedings, AND chooses the foods with the right ingredients, the fish will live a long healthy life in the 'thriving zone' rather than a surviving zone. Thanks!

    Thrive or Survive?
    Last edited by leebca; 04-20-2008 at 09:56 AM.

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