baby axoies are so cute.
Variety is the spice of life, so mixing and matching will definitely help more than trying to find a silver bullet. (I have never found anyone saying otherwise)
The above argument was rather annoying to read, because it is clear that both parties are fish experts trying to argue nutrition - a subject I know something about:
When you talk about how nutritious foods are, you refer to the % calorific content, not the raw weight.
In modern labelling this is not the case, leading to all sorts of misnomers. They are not hard to work out if you know, but most people can't be bothered. (note- these companies do this ON PURPOSE)
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e.g. FAT content
Ripples chips:
http://www.eta.co.nz/Eta/products/NutritionalInfo.aspx?id=266
Potato chips (see link if in doubt) usually weigh in at 35g of fat per 100g. One might conclude that chips were therefor 35% fat and that this was bad enough. This correct from a mass point of view, but completely misleading.
Fat has roughly TWICE the calories per gram of either protein OR carbs.
Total % of calories from fat is actually: 51% (35*2/(65+70) * 100)
Add in the fact that the rest of the chip is 6grams protein and 55grms carbs, this is NOT a healthy meal.
Actual calorific content:
Fat: 51%
carbs: 40%
protein: 4.5%
Since a well balanced diet is mainly trying to maintain a healthy carb/fat/protein ratio, these foods are FAR WORSE than they may first appear, and they appear pretty bad.
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More relevant to daphnia: eg: Soft dink
Coke has 10 grams of sugar pr 100mls (=100grams) and almost nothing else of consequence but water. By weight you would assume that coke is 10 percent sugar.
Of course this calculation is easy by calorific content:
Fat: 0%
Protein: 0%
carbs: 100%
The water is obvious not important since it is not really part of our FOOD intake. (obviously it is vital, but we are assuming you are drinking water)
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So how does this relate to daphnia??
Well if daphnia is 98% water, we can likewise ignore this content. What we really want is its calorific content and how this relates to others measured the same way. ("dry weight" is usually quoted for this reason, but with daphnia and shrimp, they contain significant %'s of ash )
Protein content by dry weight is 20-25% in adults and over 50% in juveniles.
Daphnia (wet weight):
Protein: 4% (or grams/100grams)
fat: 0.54%
Carbs: 0.67%
Thus the nutritional makup by calorific content is:
fat: 18.5%
carbs: 11.5%
protein: 70%
Brine Shrimp:
From: http://www.artemiaworld.com/
Wet weight:
Protein: 65% (or grams/100grams wet)
Fat: 6.8%
Carbohydrate: 25.0%
Ash: 4.4%
Moisture: 8.0%
Calorific breakdown:
Fat: 13.1%
carb: 24.1%
protein: 62.7%
Not much difference at the macro level really.
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This all has to be taken with a grain of salt of course. There are many more factors to nutrition than just fat/carbs/protein. What types of fats are important as well as vitimins and so forth.
Since I doubt anyone here has a "reccommended daily intake" of vitimins for any of their fish, let alone for these critters, this is probably not something you can investigate.
Common wisdom for fish will most likely not apply to a meat eating salamander anyways!? (they love red meat apparently, fish cannot handle the saturated fats)
Again, this is WHY variety is important!
Further, Daphnia have other physical advantages. They are fresh water and can live in a fresh tank until eaten, unlike brineys. Less chance of parasites and bacterial infections. (I believe - I am not an expert) Easier to grow. Cheaper...
Even if brine shrimp turn out to be a little better, are they really worth the increased expense? Will it actually make that much of a difference?
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lol. And as i am writing this, we just got given free left over pizza - it is one thing to know the nutritional value, it is another to resist the cheesy goodness....