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News & Reviews Article
| Title |
Fish Foods: Fresh vs. Frozen vs. Freeze Dried |
| Author |
Ralph Cabage
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| Last Updated |
2014-12-13
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| Abstract |
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Fish Foods: Fresh vs. Frozen vs. Freeze Dried
There are varying opinions about which types of food offer fish more nutrition. Some fishkeepers swear by live foods while others shy away from them for fear of releasing pathogens into their tanks. Surprisingly enough, whichever method you prefer probably suits your fish just fine.
Fresh foods are not always nutritionally superior to frozen or freeze-dried foods. Keep in mind the condition of the organism when it goes through the process. If a bloodworm is healthy and full when it is frozen, it will contain more nutrition than a live bloodworm that is unhealthy. Of course, if the healthy bloodworm is allowed to thaw and be refrozen multiple times, that nutritional value decreases significantly. If both bloodworms are in a healthy state, then it is true that the live bloodworm will possess a little more nutritional value than the frozen one.
The freezing process itself does not affect the nutritional content of the food like most people think. Though both forms of freezing (liquid nitrogen and frigid air exposure) cause cell walls to burst as the water in them expands, the nutrients are not necessarily lost. They either remain in the liquid that results from thawing or are sealed in with binders added to the frozen foods. If the nutrients are not sealed by a binder, then those nutrients are likely lost as the fish cannot process them when that liquid is released into the aquarium. But if the food does have the binder, then the food loses little to nothing in the freezing process, making the food perfectly acceptable in nutritional status.
Some aquarists believe that freeze-dried foods have a higher nutritional content than frozen food. This is actually wrong, and nutrition labels on these foods is what causes the confusion. Comparing nutrition labels from a package of frozen brine shrimp to a package of freeze-dried brine shrimp seems to display that the freeze-dried package is a better nutritional choice. However, the nutrition labels found on fish foods are not designed the same way as nutrtion labels on human foods. Human food labels are based on a pre-serving basis while fish food labels are not. There is no way to determine a basis when fish needs vary so much. For instance, a damsel could not handle the amount of food a full-grown snowflake moray eel requires. The labels on fish food actually give information about the amount of nutrients the organism (i.e. brine shrimp) contains and are not based on a standard serving size.
When choosing between freeze-dried or frozen foods, keep in mind that both have a similar shelf life. As long as the moisture and oxygen are kept away from the freeze-dried food, the lifetime of that food is indefinite. The problem is that keeping these foods dry is easier said than done, leaving many to believe that there is a major difference in shelf life between the freeze-dried and frozen foods.
And though many fishkeepers think that preserved foods are safer because pathogens are killed in the freezing process, pathogens can be introduced from all food sources. Again, it depends on the health of the organism before the process. There is still enough liquid after the freeze-drying process for pathogens to survive. They may not be able to reproduce, but they do not die. Freezing the food only keeps the pathogens dormant until a warmer temperature is reached. Either way, these methods of processing do not guarantee a pathogen-free food.
In other words, all fish foods (whether alive, freeze-dried, or frozen) contain almost the same amount of nutritional value. The differences between the choices is minimal and not enough to cause concern. If there is any question about the fish obtaining enough nutrients, additives can always be used.
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