 Page 7 of 11 Hormones:
Variety Is The Spice Of Life?
When it comes to this question the majority of hobbyists tend to express in unison "Variety is the spice of life" or "Would you want to eat the same food all the time?" These are all human interjections. In captivity, many marine butterflyfish that consume only coral polyps in the wild, would rather starve to death than switch food. Harlequin Shrimp eat only the feet of the Starfish, Monarch Butterflies (caterpillar) eat only milkweed, and Koala Bears eat only Eucalyptus leaves.
As long as the one food can sustain the fish in a thriving condition, this should not be an issue. Fish are creatures of habit; they are simply not capable of getting bored.
While the information gleaned from these aquaculture studies is basically sound, the majority of this research involves fish that are being raised for human consumption. With the exception of the color of the flesh of certain species such as salmon, trout and shrimp, the overall coloration and longevity of the animal is not a primary concern. Unlike most tropical species, fish raised for human consumption have a very short life span. In light of this, food that's designed for warm water Tropical fish has to be modified to ensure that a lower amount of lipids is used, high quality marine proteins are used as the main source of protein, and a wide array of natural color-enhancing ingredients must also be supplied via the diet such as Krill (Euphausia superba dana), Spirulina algae (Spirulina platensis), natural Astaxanthin (Haematococcus pluvialis), etc.
Flakes vs. Pellets:
Any discussion that involves fish food deserves a brief explanation on these two types of commercially prepared foods. While flakes have been the most popular type of food for the past 50+ years for hobbyists, commercial operations learned a long time ago that pellets are the superior choice for all feeding applications.
By their very design, flake foods are paper-thin; absorb water very quickly, and while doing so leach out much of the water-soluble vitamins in a very short period. Some studies suggest that once flakes are added to the aquarium, the majority of water-soluble vitamins (such as vitamin C) are leached out of a flake food within 60-90 seconds.
This information has been common knowledge in the aquaculture circles for several decades, yet some hobbyists seem to be stuck using outdated and less than ideal methods for feeding their aquarium raised fish. Using pellet food for all feed applications is yet another concept that has been proven in commercial aquaculture since its inception. |
In the United States the use of male hormones (testosterone) in fish foods is highly illegal, and for good reason. Long-term use of steroids in fish food has been associated with skeletal deformity, increased susceptibility to infections, and pathological changes in the liver, kidney, and digestive tract. Females that are fed sex steroids will "color up" to the same degree as their male siblings, and juvenile males can become fully colored at a very early age. The downside is that once removed from a diet supplemented with hormones, the females will lose their color, possibly become sterile, and often times the males will also lose much of their color, and never regain it. High quality fish foods contain natural color enhancers that are found in nature, which allow the fish to gain maximum coloration as they mature. The ideal goal for a fish food manufacturer should be to mimic what is found in nature, not a laboratory test tube.
Can fish thrive on one food? The answer is yes! Fish do require a varied diet, but if that one single food is made from a wide variety of high quality raw ingredients, the varied diet that many hobbyists seek can indeed be found in one single formula. If one was to take all of the various ingredients found in a typical wide variety of formulas, and create a food that contained all of these various ingredients in a proper ratio and balance, would it not be the same as feeding all of these foods separately? If only high quality premium ingredients are being used, in many cases that single food might actually be much better for the fish. 
This concept has been proven in commercial aquaculture since its inception, and there is certainly nothing new to feeding fish a complete and balanced diet by using a single food. The aquaculture industry has been doing just that for the past century. What many hobbyists fail to realize is that the aquaculture industry is responsible for the vast majority of the science that all commercial fish food manufacturers use when formulating their various foods for tropical fish. 
Pellets are preferred over flakes due to the fact that they are more nutrient dense, and much more stable in water. For species of fish over 2-3 inches, pellets are clearly the most optimum method of providing nutrition to your fish. Not only can you feed much less on a volume basis, but pellets will also remain stable in the aquarium for an extended period of time.