Browse Quick Guides by Subject

Proper Feeding for Your Saltwater Fish

Proper Feeding for Your Saltwater Fish

Share this with your friends

A well-balanced diet is an essential part of a marine animal’s health—this goes for fishes, corals, and other invertebrates. Improperly feeding your saltwater fish is the number-one cause of death in the marine aquarium hobby. Here is what you need to know to properly feed your fish, whether they eat meat, plants, or anything in between.


Carnivores, not surprisingly, eat flesh. They need plenty of protein in their diets. Proteins are made up of amino acids, and these amino acids are critical to carnivorous fishes and invertebrates, including corals.

Carnivorous marine animals appreciate live food or fresh meaty seafood. The most common foods in the category include the following:

In addition to prepared carnivore food, it is also good to feed meaty seafood to our carnivorous marine animals. Many of these foods are available at your local fish store or online.


Marine herbivores are generally not strict vegetarians. Most herbivorous marine animals rely on at least a certain amount of meaty seafood in order to get enough protein. This meaty seafood usually comes in the form of small crustaceans consumed accidentally when feeding on herbivorous food. Nonetheless, herbivorous foods should be made available to herbivorous marine animals. The most commonly available herbivorous foods include the following:

Many aquarists also offer their herbivorous livestock lettuce, spinach, kale, and other leafy greens.


Most of the marine aquarium animals we keep are omnivores. In fact, it could be said that all marine fishes are omnivores, as they all feed on planktonic animals during at least some stage of their development. There are many prepared foods for omnivorous marine animals, or you can combine foods from the above lists to make sure your omnivores are getting a well-balanced diet.

Prepared Foods

There is a virtual cornucopia of prepared foods for marine animals readily available. Some are quite good, although many are more about marketing than nutrition. Basically, prepared foods come in the form of flakes and pellets, sheet food, freeze-dried food, and frozen food.

Flakes and Pellets

Flake foods are the most commonly fed foods in the marine aquarium world because they contain a balanced assortment of carnivorous and herbivorous food in an easy-to-store and easy-to-feed product. If you want to feed flake food to your marine animals, make sure it is a flake food specially prepared for marine animals. Using a freshwater flake food will usually result in malnutrition over an extended period of time.

Pellets also contain a balanced diet, but they are designed to either sink or float. Sinking pellets are good for animals that are bottom dwellers or not aggressive enough to join the feeding frenzy at the surface.

With both flakes and pellets, read the ingredients. You will want to see a combination of fishmeal, Spirulina, tubifex worms, algae, and other yummy treats. By looking at the color of the flakes, you can make an educated guess about the proportion of certain ingredients (green flakes are full of vegetable matter, red flakes are full of protein, and multicolored flakes are mixed). Flake and/or pellet food alone is not recommended for marine animals, but they can be used as part of a balanced diet.

Sheet Food

Sheet food comes in sheets and may be prepared for marine animals or for humans. The most common sheet food used by marine aquarists is nori, which is often sold in the oriental foods section of your local market. Nori is kelp and is used in making sushi. It happens to be an excellent food source for marine animals in the aquarium as long as it has no additives or preservatives. Various manufacturers also make sheet food especially for marine aquarium fishes.

Freeze-Dried Food

Freeze-dried food has had its moisture sucked out of it, yet most of its nutritional value remains. Freeze-dried foods are preferable to frozen foods (although the latter are generally cheaper). Freeze-dried krill and tubifex worms are popular, but arguably the best freeze-dried food currently available is freeze-dried copepods. A product called Cyclop-eeze should probably be in every marine aquarist’s home.

Frozen Food

Frozen foods are widely available, and they are generally quite nutritious. You can purchase a variety of preparations ranging from frozen foods designed for specific species of marine animals to frozen foods representing a specific food source. Keep in mind that freezing does have a negative effect on the nutritional value of the food, and, for this reason, soaking all frozen foods in a vitamin supplement like Selcon is recommended; this provides not only vitamins but also fatty acids that are missing in your frozen foods.

How to Feed

Depending on your fish, you will have a regimen of feeding that suits each animal’s dietary needs. In general, it is best to feed a very small amount of food several times a day. It is also a good idea to vary what you feed. A well-balanced flake food in the morning, a small sheet of nori midday, and freeze-dried or frozen food in the evening is one example. You may choose to replace the freeze-dried or frozen food with small pieces of meaty table seafood several times a week or live food such as newly hatched brine shrimp (Artemia spp.).

Once again, it is important to research your species’ dietary needs.

Some marine animals will need special attention at feeding time. Corals and other sessile invertebrates, for example, cannot move to the food, and so you must often move the food to them. While many corals host algae, which in turn provide the majority of their food, almost all corals benefit from targeted feedings of either a specially formulated, invertebrate food or small pieces of meaty seafood. Plan to deliver this food with either a feeding stick or a turkey baster.

Overfeeding is generally more of a problem than underfeeding, but underfeeding can also lead to serious problems. In addition, feeding your saltwater fish the right amount of the wrong kind of food will lead to definite problems. There are all sorts of rules of thumb for how much to feed, but no single piece of advice outweighs the value of knowing your species’ needs. Have fun!

From The Complete Idiot’s Guide to Saltwater Aquariums by Mark W. Martin and Ret Talbot