As the most numerous animals, in terms of both species and individuals, insects form a large part of the diet of a wide variety of freshwater fish. Many insect species are also readily taken by marine fish and invertebrates. Fortunately for the aquarist, a number of insect species are commercially bred and many others are quite easily collected.

House Crickets (Acheta domestica)

House crickets have been commercially bred for use as food for pet reptiles and amphibians for many years. Their use as a fish food has, however, been largely overlooked. Many freshwater fish eagerly accept crickets, and they should figure highly in the captive diets of such species. Freshwater invertebrates such as crayfish and aquatic insects, as well as many marine fish and invertebrates will also eagerly accept this nutritious insect. Even tiny fish such as guppies will relish a cricket that has been crushed to provide them access to the body cavity.

Obtaining Crickets

Many pet stores stock crickets in several sizes, including newly hatched (called “pinheads”), 10 day old, ½″ size, and adult. Commercial cricket farms, which usually advertise in magazines devoted to reptile and amphibian husbandry, will ship large quantities of whatever size you might need. Purchasing crickets in this manner will generally be much less expensive than buying from pet stores.

Nutrient Loading

Unless you are certain that your supplier has fed the crickets well, you should keep your crickets on a high quality diet for two days or so before feeding them to your pets. This step will ensure that your pets will obtain optimal nutrition from the crickets that are consumed. The crickets should be fed tropical fish flakes, trout chow, or a commercial cricket diet. Apples, carrots, oranges, and banana skins should also be provided as a source of water as well as nutrition. Note that house crickets require water to drink but are generally tolerant of damp conditions and will quickly die if not kept dry. Normal room temperatures are adequate for their maintenance but be aware that they can be quite noisy.

Using Crickets

Crickets may be fed to all manner of fish and invertebrates but are especially favored by insectivorous freshwater species such as sunfish. They should compose a large part of the diet of insect specialists such as the West African butterfly fish, Pantodon bucholzi. In cases where crickets are used as the basis of a fish's diet, it is especially important that the crickets themselves are maintained on high quality food, as described above.

Breeding Crickets

House crickets may be bred in captivity, but the task is labor-intensive. Crickets are ravenous predators of their own eggs, so the egg laying sites (plastic containers containing damp soil) must be removed often. In most cases, it is preferable to buy the crickets, feed them for several days and then use them as food for your pets.

Collecting Crickets

Free living crickets of many species are common worldwide and will provide an excellent treat or dietary supplement for your aquatic pets. Crickets may be collected by overturning boards and rocks in grassy areas or by luring them into cans buried flush with the earth and baited with a small amount of molasses or ripe banana.

Mealworms, Tenebrio molitor and Zoophobia spp.

Long a dietary staple for captive reptiles, amphibians and birds, mealworms are of much use to the aquarist as well. They are commercially available in sizes ranging from hatchling to adult. Fully grown Zoophobias, sold as “super mealworms,” are large enough to tempt such sizable fish as the largemouth bass, Jack Dempsey, and oscar.

Colonies of mealworms are fairly easy to maintain. The worms themselves are actually the larvae of various species of beetle. They should be kept in several inches of oatmeal, cornmeal, and dry baby food. The colony should be kept dry, with the only moisture being provided in the form of slices of orange, apple, and potato. The adult beetles may be retained as breeding stock or fed to larger fish.

Tenebrio molitor, the smaller of the mealworm species, may also be stored in a refrigerator until needed. The largest species, Zoophobia, is native to warm areas in South America and does not tolerate refrigeration well.

Waxworms (Galleria mellonella)

Superficially resembling legless maggots or beetle grubs, waxworms are actually caterpillars that live a unique and specialized existence within beehives. They are a pest on commercial honey farms, where they are harvested for use as fishing bait. In recent years waxworms have become quite popular as food for pet reptiles, amphibians, and birds and are now readily available in pet stores.

Due to their specialized diet, waxworms are quite difficult to raise (unless, of course, you happen to own a bee farm!). They do, however, survive for quite long periods in the refrigerator. Waxworms are eagerly accepted by all manner of freshwater fish and invertebrates, and by some marine species as well. The exoskeleton is fairly thick, so you may need to crush the waxworms when feeding small fish.

Waxworms are supplied packed in sawdust or wood chips. Unfortunately, these materials stubbornly adhere to the insects themselves. You should, therefore, be careful to brush the sawdust from each insect before feeding your pets, lest they ingest this potentially harmful material or it blocks filter intake tubes.