Frank Indiviglio - The Everything Aquarium Book: All You Need to Build the Acquarium of Your Dreams

The use of alternative food items and smaller invertebrate species takes on greater importance when you are maintaining small, specialized animals or raising particularly delicate fry. The commercially available diets for such creatures might be limited to one or two items, so you must look elsewhere to arrange a balanced diet. For less demanding captives, live foods are less critical, but they do provide much-needed dietary variety and may help stimulate reproduction. Experiment, if possible, with untried food animals and attempt to establish breeding colonies of those that show promise.

Tadpole shrimp are tiny crustaceans that superficially resemble shrimp and, much like brine shrimp, are adapted for survival in extremely harsh environments. Some species complete their entire life cycles within one week, because they live in desert pools where water may collect only once every three or four years. Tadpole shrimp are generally considered to be freshwater animals, but the tiny pools that they inhabit may contain a good deal of salts and other minerals. Many species will therefore survive for a time in saltwater aquariums. Tadpole shrimp cultures may be purchased from biological supply houses but are generally not available in pet stores.

Fairy shrimp are closely related to tadpole shrimp and also dwell in temporary freshwater pools. Although not commercially unavailable, large numbers may be collected when conditions are right. In temperate areas, they gather in huge breeding groups during the late winter and early spring. You may be surprised by the very cold temperatures in which they will remain active. As always, check into the legality of collecting fairy shrimp before doing so.

Seed shrimp, also known as Ogtracods, are worldwide in distribution and are among the most common crustaceans to be found in fresh, marine, and brackish waters. They do not so much swim as bounce along the bottom of the aquarium, close to the substrate. This habit renders them an ideal food for small, bottom dwelling fish and invertebrates. Although not often bred as a food source for aquarium animals, seed shrimp are resilient in captivity and will thrive on a diet of algae pellets, liquid invertebrate food, and finely ground tropical fish food flakes.

An innumerable variety of tiny animals and plants, many of them invisible to the naked eye, form the basis of the food chain in the worlds fresh and marine waters. This conglomeration of diverse organisms is loosely referred to as "plankton" and the larger species are an excellent and often vital food for tiny fry and filter feeding invertebrates. Plankton is most easily collected by using a mesh plankton net. Available through biological supply houses, these nets can be used from the shore and are also manufactured in styles that can be towed behind a boat. The use of plankton as a food source will greatly improve your success in breeding and raising a wide variety of otherwise delicate aquatic creatures.

Daphnia are tiny crustaceans that may be collected using a plankton net or purchased from biological supply houses. In the alternative, you may start a culture by adding pond water and some dead leaves or hay to a jar or aquarium that is placed in a sunny location. The largest and most often available species, Daphnia magna, reaches a length of 0.25 inches and does best at temperatures of 75F to 80F (23.6 to 26.6C). Most species of daphnia mature within one week, with adult females being capable of producing 100 or so eggs every few days. Daphnia can reproduce without the presence of males. Daphnia can be fed algae tablets and liquid foods sold for filter feeding invertebrates. They do best in aerated aquariums that support a growth of algae. Due to their small size, daphnia will be drawn into the intakes of most filters, so filtration is best achieved using live plants and algae, water changes, and possibly a sponge filter.

If you use pond water and bottom debris to establish your daphnia colony, check for the presence of the larvae of dragonflies and other predatory insects, and for pests such as fish lice.

Copepods are another of the many crustaceans that are excellent food sources for the smallest of aquarium inhabitants. Copepods may be found throughout the world in both fresh and marine waters, with more than 5,000 species having been described to date. One of the most commonly encountered species is Cyclops fuscus, which grows to 0.125 inches in length.

Copepods may be collected and cultured in the same manner as has been described for daphnia.

A number of large marine worm species are seasonally available at bait stores. Unfortunately, these worms are not cultured in captivity and thus are wild collected and quite expensive. You might consider their use, however, as a supplement for particularly valuable large marine fish. Be aware, however, that several types possess very sharp mouth parts that can deliver a painful bite to yourself and your pets. Ask the dealer about this and remove the heads of any potentially dangerous species before feeding them to your pets. Marine worms may also be collected by searching under rocks at the very edges of bays, lagoons, and oceans. Most marine worms will survive for several weeks if kept refrigerated and packed in damp marine algae.

Microworms, Anguillula silasiae, are not true worms but rather invertebrates known as nematodes. They require temperatures of approximately 75F (23.6C) and will feed upon vegetable-based tropical fish food flakes. Microworms thrive well in damp peat moss.

Grindalworms are annelids and are closely related to earthworms. They can be cultured as has been described for microworms.

Whiteworms are also available commercially and do well when kept in peat moss and fed on a diet of moistened oatmeal and fish food flakes. They require cooler temperatures than do the species formerly described, faring best at 50F to 55F (9.9C to 12.7C).