Flakes and pellets

About flake feeds. I don't cut corners in choosing flake feeds. I buy the most complete standard fare from one of the big long-established suppliers. I compare the ingredients listed on the labels. Commercial flakes from the large familiar manufacturers are all nutritionally complete. They include stabilized vitamins that retain their potency in cool dry storage. My skeptical instinct is to avoid "color-enhancing" flakes or ones that are "specially formulated" for cichlids or bettas and go for best-quality, general-purpose flake feeds.
 
Commercial flake fish-feed is formulated a little on the rich side, partly owing to consumer pressure. Though we feel we should be looking for a high-protein flake, herbivores are healthier with less than 25% protein in their diet. Carnivores demand a higher percentage of protein (40%) and so do juveniles that are still rapidly growing. Career biologists concerned with fish nutrition tend to be focused on maximizing rapid growth of juvenile catfish destined for the barbecue, not on a lean and thrifty Tiger Barb celebrating its eighth birthday in your aquarium. Only you can judge whether a flake feed "specially" formulated for cichlids is right for your particular cichlids.
 
The idea of special "conditioning" flakes is as outdated as the prospect of getting your fish through the winter on a diet of oatmeal alone. Most modern fishkeepers condition fishes for spawning by feeding smaller amounts of a more varied diet at shorter intervals. Remember that variety in the diet isn't achieved so much by varying the color of the flake feed, or by opening one little canister instead of another, as advertising copy may suggest, but by including some additional live, frozen or freeze-dried worms, crustaceans and insect larvae. All good flakes should be supplemented by freeze-dried and live foods, frozen foods if you like them, and often some vegetable matter. Commonly, only an admixture of live foods encourages many fishes to come into breeding condition, and live foods are essential for raising most fry. Once they reach a good part of their full size, you may be able to wean many fishes onto flake feed.
 
Color-enhancing foods will usually contain carotenoids, such as astaxanthin, which makes salmon flesh and cooked lobster shells pink. Carotenoid pigments deposited in the chromatophores in the fishes' skin help produce red, orange and yellow colors in fish. Carotenoids are a large group of fat-soluble pigments that occur naturally in connection with photosynthesis in cyanobacteria, algae and plants and are also produced by other bacteria, yeasts and molds, which use them as anti-oxidants.
 
Animals, on the other hand, cannot synthesize carotenoids and have to pick them up in their diet. Are you old enough to remember how the captive flock of flamingoes at Florida's Hialeah racetrack lost their pink tint but got back their rosy glow when krill was added to their diet? Krill, cold-water marine shrimp, feed on single-cell algae and concentrate the carotenoids in their tissues; so krill becomes a rich source of carotenoids that is often included in "color-enhancing" feeds.
 
Color-enhancing ingredients won't be able to enhance "structural" colors, such as blues and greens, nor will melanin normally be affected by diet.
 
L-carnitine. A decade ago Tetra  introduced Tetra Min Pro, a chip rather than a flake, baked at a low heat (75ºC), to pasteurize it without degrading some of its ingredients, according to advertising in the UK. It has the vitamin-like nutrient L-carnitine, "an exclusive ingredient that has been proven to enhance fish metabolism" and is said to render the chips "more digestible, with less fish waste."  You must decide for yourself whether fish feces are a nuisance to be minimized, but some roughage, which gives "body" to feces, is essential to long-term fish health.
 
 
I thought I ought to look into L-carnitine. L-carnitine. it appears, is a water-soluble vitamin-like compound that is readily synthesized by vertebrates (including fish) and easily obtained from meats. It first achieved prominence  in the diets of strictly vegetarian ('vegan") athletes, but L-carnitine is also the enhanced fat-burner in some late night infomercials, so some of the L-carnitine presentation on the web belongs in your "Staying Young Forever" file. To help you decide whether your fish would benefit from some extra L-carnitine in their diet, go to the Lonza website, where the Swiss-based leading producer of this supplement presents some information on animal nutrition (click first on "Applications" then on "Patents.")
It appears that trials of L-carnitine in fish culture produced conflicting results.
 
Phosphates. The phosphates in feed are the main source of phosphorus entering the aquarium ecosystem. They come from fish bones and scales and cartilage that get ground up along with flesh and viscera when fish are turned into fish meal. Fish meal is generally the major ingredient of flake feeds, even, as I read in the table of ingredients, a vegetal flake like Tetra's Spirulina Tropical Flakes.
 
Though phosphate is essential to make fish bones and cartilage, fish aren't able to directly recycle the phosphate in fish meal. Most of it passes through their systems to fertilize algae and plants and so works its way back up through the food web in organic forms fish can process.
 
Reduced phosphate flakes. Recently, aquarists have become more aware of the role that high levels of phosphates play in encouraging unwanted algae. The feed manufacturers are responding to these concerns with flakes that contain reduced phosphate. Flakes with reduced phosphate, like Nutramin Max, use hydrolized fish protein, supplemented with some herring meal. In the hydrolizing process, whole fishes (by-catch of industrial fishing) are liquified in a vat of enzymes. The bones and scales are discarded. Then the slurry is passed through a spray dryer. The result is extremely digestible but contains no ash or phosphate. Similar enzyme reactors break down krill to "pre-digested plankton" in other fish feed; essentially it's a high-protein natural product, which retains the krill carotenoids essential for fish colors of red, orange and yellow.
 
Vitamins. If you are even momentarily tempted to add vitamin supplements to the water, perhaps you should revise your basic approach to the fishes' diet instead. For one thing, the metabolism of freshwater fishes isn't equipped to derive benefits from solutes taken in from the water. And besides, many vitamins are only oil-soluble.
 
Pre-soaking flake feeds may be a smart precaution if greedy barbs and tetras seem to be bloated after feeding. Don't soak long enough for flakes and freeze-dried foods to sink, just to let them re-hydrate. Then add them, soaking water and all. Good flake feed remains in one piece after it is soaked.
 
Harmless color additives do make the flakes look varied. The "eye appeal" is mostly directed at you. Fish strike at flakes largely because of odor rather than color. With the right attractants like yeast and molasses you could probably encourage fish to eat cardboard!
 
Read the list of ingredients. It should begin (highest volume) with things like fish meal, roe, liver and cod liver oil, brine-shrimp, krill and insect larvae. It should end (lowest volume) with egg yolk, wheat germ, rice, oats. Look at the protein analysis on the packaging too.
 
Of special-purpose flake feeds, Spirulina-based flakes are greedily attacked by all fishes that need some greens in their diet. In the list of ingredients on the can, spirulina should come first, as the major ingredient. Algal-based flakes may be less appealing to the hard-core carnivores. University of Hawaii researchers Harry Ako and Clyde S. Tamaru compared the palatability of flake feed marketed for ornamental fish and feed marketed in bulk for food fish; their results are embodied in the article "What is the best feed for my ornamental fish?" in the Oceanic Institute and University of Hawaii  Regional Notes, Winter 2000, pp 4ff.
 
Freshness and storage. Flake feed should be kept dry, cool and dark. The refrigerator is a very damp environment, unless you are confident of the seal on your container. For storage, you might additionally seal the top with tape. Some flake feeds come with a "best if sold before" date on the packaging: very encouraging. Another feature to look for: top-quality flakes are sealed in foil. Deterioration really begins when you break that foil seal; atmospheric humidity decomposes the vitamin content first. Of course you'd never feed flakes that smelled moldy: aflatoxins can kill fish.  
 
I try not to have more than a couple of flake feed cans open at one time. I save the dessicant that often comes sealed inside its own closed capsule in bottles of medication and keep a capsule inside each of my well-closed canisters of flake feeds. I buy the smallest practical cans, ones that will be emptied in a matter of a couple of months: which is more important, variety, bulk-purchase savings or freshness?
 
Variety. Sometimes beginners get the impression that variety in feeding consists of varying the flake diet at each feeding. For better variety I alternate flake feed with live food (usually blackworms or Grindal worms). Currently the flake menu in my cupboard is: Tetra-Min. Wardley Premium Formula Tropical Flakes. Tetra Spirulina Tropical Flakes. Hikari Algae Wafers.
 
About special fry foods. The old stand-by is "Liqui-Fry," more expensive ounce for ounce than pâté de foie gras. Its major virtue may be that it encourages the growth of nutritious "infusoria" battening upon its suspension of powdered egg, yeast, legume flour, etc.
 
At FishGeeks Laura Pylypow explains how to make your own homemade liquid fry food. Your alternatives to liquid synthetic fry foods are green water and infusoria.