Variety is the spice of life, and happy, healthy fish and invertebrates require a healthy and well-balanced diet. But how do you know if your fish are getting what they need from the food you're feeding? The easiest answer is 'read the label,'...just like you would for yourself. To understand what you're looking at though, you first have to understand a bit about how a fish body functions and what it needs to remain healthy...which is not the same as a human!
Whether you intend to feed your fish entirely prepared products or supplement their diet with live or frozen foods, it is essential to seek foods with the lowest amount of supplements and the optimal energy and proteins to create a healthy diet for your fish. My goal here is to give readers a basic understanding of the most important aspects of a healthy fish diet, so that they can select their fish foods in an educated manner.
INGREDIENTS TO WATCH FOR:
Protein utilization is dramatically affected by the limiting amino acid content and protein quality, and at least somewhat affected by the salvage of essential amino acids in the body; too much protein/amino acids can cause kidney issues and affect fish longevity. When foodstuffs have different weaknesses in their amino acid distributions, it limits the loss of nitrogen and increases net protein utilization. Good sources of amino acids include: egg, whole fish meal (menhaden & salmon are preferred), unbleached wheat flour, cyclops, fish roe, squid meal, shrimp meal, crickets/cricket flour, and spirulina algae. Bottom line: Not all sources are equal and more ≠ better.
Fats insulate organs against shock, maintain body temperature, promote cell function, and aid in vitamin absorption. They are also the primary energy source for fish, especially in the heart and skeletal muscles. A balance of Omega-3 and Omega-6 fatty acids is needed in the body, as these substances work together to promote health; however, for fish Omega-3 is the most needed…and many warm water freshwater fish do not readily produce it as coldwater marine fish can. The best fats for fish foods come from aquatic sources such as whole fishmeal (menhaden is preferred).
Most carbohydrates in the diet of fish comes from plant matter. All species of fish secrete at least some amylase, the enzyme necessary for digesting carbohydrates, but carnivorous fish are ill-equipped to process significant quantities of raw carbohydrates. However, while digestible carbohydrates spare protein for tissue building, they are not a primary energy source. Fish tend to use any sugar/carbohydrates/starch in fish food first, since they can store very little if any for later use.
Soluble fibers slow digestion, and acts as a laxative for your fish. It can be found in oat bran, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables. Fiber numbers in the neighborhood of 18-19% are healthy for most fish, including carnivores.
Higher ash content indicates a higher mineral content, particularly calcium, phosphorus, and magnesium which are necessary for osmoregulation.
Garlic helps boost the immune system, and has been shown to aid in bacterial treatment, possibly because it contains Allicin.
Artificial colors have no nutritional value and some may harm your fish. Look for foods that contain natural colorings instead: cayenne, zeaxanthin (saffron, marigold, paprika, spirulina) astaxanthin (chlorella algae, lobster, salmon, trout, krill, shrimp, crayfish, crustaceans & other shellfish), lutein, tunaxanthin, beta-carotene, doradexanthis, canthaxanthin. Some of these also have additional health benefits.
Many fish will benefit from live, frozen, or freeze-dried foods. Brine shrimp, various worms, and live insects are all healthy options though live foods are usually preferable. It is recommended that ‘feeder’ fish should be given a methylene blue bath and quarantined for 24 hours before offering them as a meal.
HOW TO FEED
No one food should be your fishes’ sole nutritional source. For a community tank, try starting with a high-quality basic flake or crumble, and switch different flake foods from day to day if possible. However, do not feed two foods at the same time. Like children, the fish will pick and choose what to eat, which defeats the purpose of a varied diet. Balance these foods with your live/frozen/freeze-dried foods to address any species-specific dietary needs. For larger fish, a pelleted food may be substituted for flakes. Soak dry foods in advance of feeding if necessary to prevent air ingestion. Foods should be offered in small quantities, no more than can be consumed in a few minutes. Some aquarists suggest fasting your fish once a week, particularly if you keep predatory species, as this mimics conditions they might face in the wild.
READING YOUR LABELS
Many labels don’t give you the full picture. When the protein, fat, fiber, moisture, ash, etc. don’t add up to 100%, the remainder is usually occupied by carbohydrates and sugars. Multiply your starch, sugar, and protein percentage by 4, multiply your fats percentage by 9, and then add to get your food’s total energy points. The number of points will indicate if your food produces the optimal amount of energy for the health of your fish. The optimum number of points is 280.
Now you have a basis to start looking for healthy fish foods!
In future issues of The Dinner Bell, I'll talk about some of the foods that I've tried, what the fish preferred, and how each one measures up in terms of optimized energy.