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Alternative Diets

The pet store isn't the only place to buy fish food anymore; try your local supermarket! Parsley, kale and collard greens are great sources of vitamin C and calcium, and green peas are a good source of vitamin E. All are usually eagerly accepted by most herbivorous fishes (and even some non-herbivores). Freeze these foods for 24 hours before feeding--never heat, as heating destroys a good amount of their vitamin content. Non-oily fish from the fresh fish market is another good food choice, especially for piscivorous fishes. You can also make a gelatin-based diet, which will allow you to combine any number of foods into one carrier. For a good fish food recipe, visit my website at


The Right Food for the Right Fish
By Frank Greco, Sr. Aquarist, New York Aquarium

I am often asked is how to feed our fishes: how much, how often, and what type(s) of food. Given the recent number of pet food recalls, which included several brands of fish food, I thought this would be a good time to discuss this topic in more depth.

Feeding fish involves more than just opening a can of food and sprinkling it over the surface of the water. First off, fish food should be appropriate for the type of fish you have. You would not feed small tetras a large pelleted food, and you would not feed piscivorous (fish-eating) fishes flake food. It's important to match the size of the food to the size and type of the fish. The natural diet of the fish should be taken into consideration whenever possible, too. Herbivorous (plant-eating) fishes, for example, should be given a diet high in plant material whenever possible.

Fish food should be fresh. The older the food, the less nutritive it is as vitamins degrade over time. I suggest buying no more food than you can use in three months and keeping it in the freezer for the best shelf life. At the same time, try to vary your fishes' diet as much as possible. Since one flake food is very much like another, you may wish to use frozen and freeze-dried foods as well as looking into alternative foods (see sidebar.)

Flaked, Frozen and In-Between

Flake food is the most popular fish food available, and is usually accepted by a wide range of fishes. They come in different "blends", some being aimed at herbivorous fishes, others at piscivorous species, while others are a somewhat balanced blend suitable for all fishes (the so-called "staple diet"). The big advantage of flake food is that it can be used to feed a wide variety of fish as the flakes are easily crushed into smaller sizes to fit smaller mouths. Pelleted foods are also popular. Much like flake food, pellets are designed for fishes with larger mouths although some companies make a micro-pellet food, suitable for smaller fishes.

Frozen foods are another option. Bloodworms, brine shrimp, rotifers, Cyclops, clam, or mixtures thereof, can usually be found at your local fish shop. Unlike flake and pellet foods, however, it's essential to make sure frozen foods are NOT be thawed prior to use, and should be fed frozen or partially thawed before putting them in the tank to retain the most vitamins and other nutrients. Break off a small piece of frozen food and place it in the tank; the fish will nibble on it until it is gone, and larger fishes will gulp down full pieces (and no, they will not get an ice cream headache from doing so). Freeze-dried foods are another option, although they are not usually as popular as the afore-mentioned types.

Live foods are another option, although their popularity is not as great as it used to be. The most common live fish foods are brine shrimp, Tubifex worms, blackworms and feeder goldfish/rosy red minnows/guppies. Live brine shrimp is really of dubious nutritional value, especially if it has been sitting around for more than a day, and should only be used as a treat or to entice a picky feeder to eat. Blackworms are probably the best of the live worms available, as they are cultured in captivity rather than collected from the wild. Tubifex worms, however, can carry a number of pathogens you would not want to release into your tank. Feeder fishes (goldfish, rosy red minnows, guppies) are also possible pathogen carriers (including fish lice) and I do not advise feeding live fishes to other fishes. Most if not all piscivorous fishes can be trained to take prepared foods, so there is no real reason to use live fishes as feeders.

The Seafood Diet

How much to feed your fish depends on the type you have. I usually advise feeding no more than your fish can consume in 5 minutes two to three times a day. This does not mean to dump in a bunch of food at one time. Rather, you want to add a little at a time, making sure the fish eat everything before adding more. The five-minute rule is only a suggestion. If your fish stop feeding after two minutes, stop feeding. More fish die from over-feeding than under-feeding, so let their appetite be your guide.

Your fish should be fed every day (adult piscivorous fishes can be fed every other day). Remember that most fish in nature feed from sunup to sundown, picking here and there, nibbling on whatever they can find. Frequent daily feedings are far better than one large feeding, and your fish will be the better for it.

Frank M. Greco is a long-time hobbyist and Senior Aquarist at the New York Aquarium. Visit him on the Web at Got a fishy situation at home? Write to Frank at He may answer your question in his next column!

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Most recent update: 10/15/07
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