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Always in season and readily available, freeze-dried foods offer the aquarist an excellent substitute for fresh or live foods.

FREEZE-DRIED FOODS. Freeze-drying preserves almost as much nutritional value as freezing, although certain vitamins may be lost in the process. Many freeze-dried aquarium foods contain only crustaceans, such as krill or brine shrimp. These foods are high in protein and are very convenient, but should not form the staple diet for marine fish. Use them as a supplement to other foods. DEHYDRATED AND FLAKE FOODS. Dehydration has been used to preserve foods for centuries. While many essential nutrients are lost or destroyed in the dehydration process, dried foods are still nutritious. Moreover, they are cheap, convenient, and certain to be stocked by any aquarium shop. Choose flake foods that are specifically made for marine fishes. Reputable manufacturers include ingredients that supply nutrients essential to the fishes for which the food was formulated. While some aquarists are scornful of flake foods, associating them with the goldfish-bowl set, many accomplished reef keepers supplement their mainstay rations of frozen and fresh foods with regular pinches of high-quality flakes. Spirulina, a blue-green alga cultivated both for captive fishes and health-food devotees, is especially appealing to ravenous grazers like tangs and makes a convenient, nonpolluting food source for the reef tank. Despite the cost savings that accrue when such flake foods are bought in quantity, it is best to purchase only a small amount at any time. Opened flake foods may lose food value or even develop mold or bacterial growth. Dried seaweed is seldom sold in aquarium shops but can be found in specialty-food stores. Look for nori, a seaweed that is used in making sushi. It consists of dried macroalgae and comes in both sheets and shreds. (The price of nori can be astronomical in some supermarkets — seek out a neighborhood Asian market for the best prices.) Vegetarian fishes, such as tangs, angelfishes, rabbitfishes, and certain damselfishes and blennies love this product, and it is a more natural and nutritious food for them than garden vegetables. FOOD ADDITIVES. With growing awareness that certain nutrients are essential for the long-term health of marine fishes and that these nutrients may be lacking from commercial fish foods, a new category of products for the marine hobbyist has made its appearance. These are food additives, designed to replace important nutrients that some

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fish foods lack. Several of these products are advertised to contain essential fatty acids, vitamin C and vitamin B12. Certain fatty acids are recognized to be vitally important in the nutrition of marine fishes. Vitamin C deficiency has been linked to a condition called Head and Lateral Line Erosion (see below). Vitamin supplementation of aquarium foods is likely to increase and improve in the future, but regard with skepticism any cure-all that recommends the addition of vitamins directly to the aquarium water. HANDLING AQUARIUM FOODS. All foods should be purchased in small quantities that will be used within a reasonable period of time (one month or less) and should be stored in the freezer or refrigerator to facilitate maximum retention of nutritional value. The same goes for food additives. Keep all foods tightly sealed, as oxygen from the air can break down valuable vitamins, and moisture intrusion can lead to spoilage. Spoiled foods can be recognized by a foul odor; mold growth produces a musty smell. Discard spoiled or moldy foods immediately. Keep frozen foods solidly frozen, thaw out only what is needed, and do not re freeze completely thawed food. Many aquarists are concerned about transmitting disease to their fishes via fresh or frozen seafoods. This is extremely unlikely. In nature, sick or injured fishes are often eaten by other fishes with no ill effects. Disease outbreaks in the aquarium can usually be traced to less than optimal water quality or some other condition that creates stress for the fishes and leaves them susceptible to infection. Feeding a fresh, wholesome, balanced diet is one way to prevent disease outbreaks.

Most of the foregoing is simple common sense. We are all taught the importance of clean, fresh, wholesome food in maintaining our own health. But many people have the notion that fishes do not conform to these nutrition basics. Certainly some species are specialized in their dietary needs, but the majority of marine fishes eat a variety of foods. It goes without saying that on the reef all the foods are fresh, whether algae or coral polyps are on the menu. The cost of food is only a fraction of the cost of setting up your aquarium, so paying attention to the fishes' diet is a wise investment in maintaining your captive ecosystem.

Head And Lateral Line Erosion

Dried and freeze-dried rations provide both convenience and concentrated nutritional values and can supplement other foods

268 Natural Reef Aquariums

Nutrition-Related Problems

HEAD AND LATERAL LINE EROSION (HLLE) has long been known to affect captive marine fishes. This condition, characterized by erosion of the skin tissue along the lateral line and around the face, is seen especially in tangs, angelfishes, and clownfishes. In the past, a variety of remedies were tried, all to no avail, based upon the mistaken assumption that the condition was due to bacterial infection brought on by poor water quality. Research has shown that HLLE results, at least in part, from ascorbic acid (vitamin C) deficiency (Blasiola, 1988). Blasiola was able to induce the condition in the Regal Tang (Paracanthurus hepatus) by feeding a diet deficient in this nutrient. Restoration of the vitamin to the diet reversed the progress of the erosion. A biologist on the staff of my company believes that a low-grade bacterial infection may accompany HLLE and that this infection should be treated with antibiotics along with an improved diet. (Lowered resistance to infection can accompany HLLE, which may explain why antibiotics sometimes help.)

Prevent HLLE by feeding fishes fresh foods high in vitamin C and adding supplements that contain this vitamin to frozen and dried foods. Vitamin C is notoriously difficult to preserve by traditional storage methods, hence the need for fresh foods and/or supplements. Green algae was excluded from the test aquariums in Blasiola's study and was added to the diet along with ascorbic acid to reverse the erosion. Those fishes that feed largely or exclusively on algae in the wild appear to be prime candidates for HLLE in the aquarium.

Sprung (1991) has also presented anecdotal evidence that elimination of induced electrical charge by grounding the aquarium was instrumental in reversing HLLE in an angelfish.

FATTY-AC ID DEFICIENCY is a slow and insidious form of malnutrition that can affect large, predatory fishes such as lionfishes. The marine fish that form the bulk of the diet of these species are rich in highly unsaturated fatty acids (HUFAs). HUFAs are essential to the health of many aquarium fishes. Feeding lionfishes exclusively on freshwater baitfish, a common practice, condemns the lionfish to an early death. To avoid the problem, feed ocean-derived foods, including fish, and use a supplement that supplies HUFAs. Cod-liver oil has been used successfully as a supplement, and Selcon, a dietary-supplement mix developed for the aquaculture industry, also gives good results. UNBALANCED DIET. Another example of what I suspect is malnutrition in aquarium fish affects puffers, porcupine fish, and spiny boxfish. I have seen cases in which these fish lose the ability to eat, specifically the ability to move the jaws, sometimes accompanied by loss of the teeth. In every case, the fish had been fed freeze-dried krill exclusively for several months before the problem developed. This is not evidence that krill is bad for fish. It is evidence, however, that an unbalanced diet can lead to problems. In nature, fishes such as these feed on a wide variety of invertebrates and smaller fishes. It is not surprising that they would suffer problems from a diet consisting of a single food. In each of these cases, the fish eventually died of starvation or became so debilitated that they were euthanized. This makes me wonder how many other problems in aquarium fish could be traced to an improper or inadequate diet.

I offer these three simple recommendations for avoiding nutritional problems:

1) Find out the natural diet of the species intended for the aquarium, and attempt to duplicate it closely.

2) Feed marine fishes the widest possible variety of foods, within the context of the natural diet.

3) Use living, fresh, and frozen foods as the bulk of the diet, and rely on other forms of commercially prepared food only occasionally.

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Starvation

Some fishes may starve not from receiving an inadequate diet but from being fed in a manner that is inappropriate to the fish's lifestyle. Yellow Tangs, along with their various cousins in the Acanthuridae, graze on algae, and this behavior is almost constant during the daylight hours. A vegetarian diet is not nutrient dense, so the fishes must eat a lot to supply their caloric needs. A "pulsed" feeding schedule, where food is available only once or twice daily, does not suit these species' needs. If the aquarium has little algae growth apart from corallines, cultivation of seaweeds should be undertaken, with the aim of producing enough to keep the tangs occupied all day, every day. Tiny tangs the size of a quarter may starve in only a short period of time; in fact, the delicacy of juvenile tangs, with or without adequate food, is probably best dealt with by avoiding specimens under 2 inches in length.

Similarly, fishes that feed on very tiny crustaceans, including dragonets, Chromis, anthiids, and Heniochus, cannot obtain enough food to satisfy their requirements when the tank is flooded with food only periodically. Dragonets seem to need a natural population of tiny crustaceans, usually found in a large, mature tank with lots of live rock and live sand, to thrive. Others in this category can be fed finely chopped prepared foods, administered by some form of automated dispenser, or they can be offered live, newly hatched brine shrimp. Morsels that these fish obtain when the other tank inhabitants receive a daily feeding round out their diet.

The Shedd Aquarium in Chicago succeeds with a planktivorous freshwater species, the Mississippi paddle-fish (Polyodon), by allowing newly hatched brine shrimp to drip slowly from a reservoir into the tank all day long. The shrimp are kept in suspension by aerating the reservoir, and the drip is controlled with an arrangement similar to that used by physicians for administering intravenous solutions.

Juvenile fishes and those with retiring habits may also starve in the aquarium if the correct environmental cues are absent. Small Pomacanthus angels, such as the juvenile Koran Angels (P. semicirculatus), may be too intimidated in their new home to feed adequately. Dwarf angels (Cen-tropyge) may also exhibit this syndrome, as may adult but-terflyfishes (Chaetodontidae). Even triggerfishes, usually thought to be aggressive, may refuse to eat if they do not feel safe. Any new specimen in this category should be observed carefully. If the fish has not eaten after three days in your holding tank and is housed with other new specimens, consider providing it with private quarters. Most of the time this will result in the resumption of feeding. After the fish has had an opportunity to become accustomed to captivity, it can be moved to the display aquarium.

Feeding Invertebrates

Adding organic mixes to the aquarium to "feed" invertebrates is a mistake. Photosynthetic invertebrates seem

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