Joe, I actually agree with much of what you just said. I have also never once stated that fish processing waste is low in nutrients. My main issue has always been how that company has presented the
so called facts.
I personally find that type of marketing, insulting, and misleading.
All raw ingredients are processed before and/or during the manufacturing process. Omega's food doesn't just magically go from raw to nice clean little pellets & flakes, so unless you are privy to their exact inclusion rates, and their manufacturing process (including temps & durations used) you really have no idea which food contains better biological nutrient value or digestibility at post processing levels.
Let me give you an example. When I look at an Omega label I can't help but wonder how is it possible for them to be using processing plant waste, which I know has a very high mineral content from scales & bones (ash), yet their total ash content is listed as only a max of 8%? In my mind, and according to how they have things listed, there is only a couple of ways to push those protein numbers down (below 50% crude protein), which also pushes the overall ash content down, and that is by using a hefty amount of carbs, such as the ingredients that tend to follow all of their fish mixes - wheat flour, and in some formulas kelp. (kelp is also very high in carbs) Yet this same company condemns not only the use of fish meal, but also the use of "a whole lot of starch (like everyone else)". Or they are listing their 'fresh fish waste" on an as-is wet basis, which would also throw their entire ingredient listings off, if one is comparing it against the vast majority of other foods that list everything on a dry weight basis.
I honestly have no idea what is going on behind the scenes, but in my mind 1+1 isn't adding up to 2.
I view ingredients, percentages, etc by using both an analytical approach, and a common sense approach. If things don't make sense, there's usually a reason.
Yes, the mineral content from bones is a good thing, but only to a certain level. High ash levels in fish food generally equates to inexpensive and/or low quality fish protein containing high amounts of bones and scales. (high in inorganic material) Your fish will utilize some of that mineral content, and the rest just adds pollution to your tank.
There is also nothing wrong with adding kelp to a commercial formula, but again, only at certain levels. If too much kelp is added to a fishes diet in captivity the food will move too swiftly through the digestion system before all of the nutrients can be gleaned from the food. In the wild this is not a problem as most cichlids that are classified as strict herbivores eat from sun up to sun down in order to acquire enough nutrition to live & breed another day. I'm guessing that the vast majority of cichlid keepers feed their fish once, maybe twice, and at the most 3 times a day.
This is not how these fish feed in nature, and the moment that one places these fish in a glass cage everything changes, including how one should go about supplying optimum nutrient levels to their fish.
I told Pablo years ago that if he created a "herbivore" pellet (with large inclusion rates of seaweed, kelp, spirulina etc, he could make millions, and he agreed, but he wouldn't do it as he knew that in captivity this is not the way to provide optimum nutrient levels to a herbivore. To me that speaks volumes about the integrity of the man behind the food.
Others look at nothing much beyond numbers, and if there's a golden opportunity to meet a supply & demand situation, they will supply what the consumer wants, even if that consumer is uninformed & confused by the massive amount of propaganda and misinformation that has been perpetuated for many years in this industry.
Using this same type of feeding in captivity logic, the vast majority of hobbyists will tell you that one needs to supply wood to plecos such as panaques or they will die. Die? Really? I have been telling people for years that panaques don't eat wood for it's nutrient value, or for digestibility, they eat it as a secondary action when scaping the biofilm on the wood. Just recently there is now science to back that up.
http://www.practicalfishkeeping.co....ome_catfish_really_eat_wood?&utm_content=html
Based on recent publications by Donovan German and his coauthors, it seems that they are not digesting the wood as was speculated in previous papers by Nelson and coauthors.
They don't seem to have a gut anatomy designed to support the microorganisms that would be needed to break down the wood and, like other loricariids, have a very fast gut passage time.
This is no different than your herbivorous Mbuna that scape the algae & biofilm in the wild. Also note the last line, about a very fast gut passage time.
Exactly what I was stating earlier with regards to feeding certain foods in captivity; "If too much kelp is added to a fishes diet in captivity the food will move too swiftly through the digestion system before all of the nutrients can be gleaned from the food."
In the wild, the cichlids found in the Rift Lakes have evolved & adapted to living in certain niches of the lake, which over time has
forced them to become specialized feeders. (as per Ad Konings) Yet all of these specialized feeders will readily eat
anything that's available. (as per Ad Konings) While a fish classified as a strict herbivore (such as a Tropheus moorii) may indeed spend its entire day scraping the aufwuchs, I can assure you that they would much rather eat a handful of worms if given the opportunity. In the wild they eat low quality foods because that's the only foods available, not because they choose to.
And while certain species such as Tropheus & various Mbuna may in fact be classified by the scientific community as strict herbivores, the reality is that even though algae dominates the stomach contents, the actual foods that make them grow are insect nymphs and larvae, crustaceans, snails, mites, micro-organisms, and zoo plankton, not vegetable matter. (as per Ad Konings)
Their long digestive tracts are designed as such so that in nature they can break down the complex plant matter that they consume, which doesn't mean that they can't properly assimilate
more easily digestible forms of protein. Apparently this is a concept that some hobbyists fail to grasp.
Keep in mind that the vast majority of fish are opportunistic feeders, and are all omnivorous to a certain extent. Cichlids classified as carnivores don't just eat meat, any more than a herbivorous cichlid just consumes vegetable matter.
I look at it this way, all wild fish are opportunistic feeders, and will eat pretty much anything that comes their way, and while herbivores may in fact consume large amounts of plant matter, and carnivores may in fact eat large amounts of fish based foods, that plant matter generally contains certain amounts of nymphs, larvae, crustaceans, snails, mites, micro-organisms, and zoo plankton, and the smaller fish that the larger carnivores consume are typically gut loaded with phytoplankton (which consists of microscopic plants), so in actuality all of the Rift Lakes cichlids consume the same
types of protein, fats, carbs, etc, just in varying degrees.
If you really feel the need to supplement your herbivores diet in captivity, or are concerned about gastrointestinal issues caused by whatever, my advice would be to crank up your lights & allow a nice algae bed to form on your rocks. If nothing else it will allow you to witness their natural grazing/feeding behaviour, and at the same time keep some of the more aggressive fish occupied on something other than other fish.
