Aquarium Fish Nutrition

Feeding fish seems to be a simple topic and in a way, it is. Many fish survive for a long time on a simple diet of the cheapest flakes available at the pet store. But as you will soon discover, aquarium fish nutrition is very important for their long term survival.

However, there is more to the matter than this. For however beautiful and active an aquarium fish is on generic flakes, it will be more colorful and more active if it is given a healthy, varied diet that matches its nutritional needs. The makers of the generic flakes make a single type of flake which is marketed for the majority of fish. These fish run the gamut from almost totally herbivorous to almost totally carnivorous. How can one flake adequately provide proper nutrition for carnivores, herbivores, and omnivores? In short, it can't. Providing the fish with such a diet is similar to a human living on nothing but chicken nugget meals at fast food restaurants and supplementing it with vitamin pills. It provides little nutrition other than empty calories, and the vitamins are not a good source of extra nutrition.

There are several things to consider when feeding fish. The form that the food takes, the ingredients of the food, and what type of food the fish needs are some of the most important things. I will be focusing on the first two, as the last varies from fish to fish, and there are too many fish in the aquarists' world to cover in one article.

Types of Fish Food

Dry Fish Food

This type of food includes flake, pellet, stick, and sinking. All of these foods are based on a mash of the ingredients that are shaped into whatever form and then dried. The advantages of such foods are simplicity and cost. They can be stored for a long time, a single bottle lasts for months, meaning even high quality food ends up being affordable. Unfortunately, even the best of dried foods must suffer some processing, which is bound to cause a loss of vitamins and minerals.

Freeze-Dried Fish Food

This includes blood worms, Krill, daphnia, and a large number of other terrestrial and aquatic invertebrates. These foods are excellent treats for many fish, and are good base food for some carnivores. Freeze-dried foods are almost guaranteed to be free of contaminants that are sometimes a concern with live and frozen foods. For a person who is considering holistic health and nutrition, freeze-dried foods are a step down from fresh or frozen, but are still a step up from flakes and pellets.

Frozen Fish Food

This is very simply whatever ingredients frozen. Often, it's frozen into little blocks that are more easily cut apart. To use, you merely cut off what you need, let it thaw, and feed to the fish. This food is full of the ingredients' original nutrients, with nearly nothing lost in the minimal processing. There have been reports of disease being introduced via frozen foods. Many bacteria and viruses are capable of surviving freezing, allowing this to happen. In a healthy tank, such an introduction is unlikely to cause harm, but it is still a possibility.

Fresh Fish Food

This can range from cut up bits of pea (an excellent laxative for fish, as well as a good source of vitamins and minerals) to a slice of zucchini for sucker-mouth fish to a bit of raw shrimp or beef for a carnivore. Almost every fish loves fresh food of one kind or another. Vegetables can be softened by parboiling. This breaks down the cell walls, making the vegetable more appealing and more easily eaten by fish.

Live Fish Foods

A controversial subject for many reasons, the use of live food is still an important topic. A few carnivores are notoriously difficult to wean off of live food, and may become stressed if they lack the chance to hunt. Live food includes various worms and insects, as well as fish, most often guppies, Mollies (sometimes in saltwater tanks) or goldfish. Aside from personal squeamishness, the biggest problem with live foods is the potential for introduction of fish disease. This can be mitigated by finding the healthiest examples of live food as possible. Many carnivores respond to live food in a way that they don't respond to any other food. Happy fish are healthy fish, so if you have dedicated carnivores, it may be worth giving them periodic live treats, at the least.

A Special Note on Feeder Fish

Feeder fish need to be discussed separately. The fish that are sold at nearly every pet store as "feeder fish" are, perhaps, the single worst food that one can offer. I feel that food that is closer to the original source is better. These poor creatures are the exception. They are kept in severely overstocked tanks, even by fish store standards, and are heavily stressed, exposed to disease, and are literally soaking in nitrates, if not ammonia. Because of this, their bodies burn off vitamins and minerals in an attempt to remain alive. The end result is a toxic, disease-ridden meal that contains nothing but empty calories. In addition, this is torture for the feeder fish. Whether or not they will become food, they are no different from the fish you keep in your aquarium. A piece of raw shrimp, salmon, or beef heart is a far healthier meal for a piranha or other carnivore than one of these fish.

If you want to provide something for your fish to hunt, consider raising your own fish. Guppies are a popular choice for this, as they are fast breeders. Do not allow the tank to become overstocked (consider selling extra fish as quality feeders to other aquarists), feed the fish properly, and keep up on water changes. This will provide a much healthier meal for your carnivorous fish.

Homemade Fish Food

This can fit in most of the above categories. It involves mixing your own food (I find that a Magic Bullet blender is great for doing this) and freezing, drying (bake in an oven at low temp), or feeding it to the fish while it's raw. Some good additions to homemade food are Spirulina, nori (sushi wrap), zucchini, peas, raw shrimp, bloodworms, krill, and Cyclopeeze (an engineered planktonic critter that is high in protein and nutrients). Gelatin is a good binder to hold foods together in the tank.

Finding Good Quality Fish Food

Although it would be possible to determine the best food for your fish by tracking nutrient levels in each food, this is extremely difficult, as there aren't the same packaging requirements on pet food as there are on food packaged for humans.

An easier way is to keep a list of ingredients to avoid and a list of ingredients to try to include. I use a similar method to pick food for my cats, and to pick food for myself.

Ingredients to Avoid

This one is mostly simple. Avoid any "meals". Fish meal and shrimp meal are the most commonly used in fish food. The problem with these products is that "fish meal" can be made from the skin, bones, and offal of fish. "Shrimp meal" can be made from the shells and tails of the shrimp. This carries very little nutrition, and is just empty calories.

A few other ones to avoid are artificial flavors, excessive preservatives, and, in my opinion, excessive amounts of added vitamins (these will show as long lists of chemical names). Some added vitamins are needed, but if the list of vitamins is three times as long as the list of actual food products, I would question the inherent nutrition in the food products. Studies have shown that animals are more efficient at processing minerals and vitamins from natural sources than from artificial additives.

Ingredients to Include

Spirulina. This superfood is a type of cyanobacteria that contains a wealth of minerals and vitamins. In general, the darker color a vegetable has, the more nutrients it contains. Spirulina is such a dark green that it almost appears purplish black.

Whole fish, whole shrimp, whole anything. This is the opposite of fish meal or shrimp meal. It contains the entire fish. In other words, it contains what a predator would eat.

Kelp (or other sea vegetable). Just good, wholesome veggies.

Garlic. Garlic is used to help many different problems in fish, so it's a definite plus in any food.


The last thing I'm going to talk about is supplements. The best of these are concentrations of the best parts of plants and animals. As I said above, I prefer that my pets get their nutrition from a natural source. These supplements are among the best way to do so. A good vitamin supplement will look organic, rather than being a homogeneous liquid. The best way to add this to the fishes' diet is to soak their food in it before feeding. It can be added directly to the water, however.

Garlic juice is another additive that many use. In addition to being good for the fish, it makes food irresistible to most fish, making it useful in getting a finicky or sick fish to eat. As with supplements, it can be added to the food, or directly into the water. Though you can buy garlic juice bottled specifically for aquaria, you can also use the juice from jars of minced garlic for the same effect.

There is much, much more to feeding your fish than what is printed here. These guidelines will serve you well, however, in beginning to keep your fish healthier. They will show brighter colors and more activity. They will be more resistant to disease and parasites, and will live longer. In short, they will be happier, which will allow you to enjoy them that much more.

About the Author:

Sam Hirte-Runtsch - Started keeping fish when I inherited a tank from a friend's girlfriend. Have since purchased three other tanks, each with an entirely different setup and type of fish.

Related Articles
Fish Food for Dummies