I think I am going to have to agree with Al on this one!
I took an aquaculture course while in university and in my text it says "Rotifers and many strains of brine shrimp have very low levels (or total lack) of certain essential fatty acids (EFAs) that are required for normal growth and development of marine larvae. To overcome these deficiencies, EFA content of rotifiers and brine shrimp has to be manipulated using fatty acid enrichment techniques. This process involves feeding a nutrient source rich in EFASs (e.g. microalgae, oil suspensions etc.) to the rotifers or brine shrimp prior to feeding them to cultured larvae. Enrichment of rotifers and brine shrimp boosts EFA intake, resulting in improved survival and growth rate (from Aquaculture: farming aquatic animals and plants by Lucus & Southgate)."
OK, the facts on adult brine shrimp versus newborn:
Adult:
- Protein 56.4
- Lipid 11.8
- Carbohydrate 12.1
- Ash 17.4
New Born:
- Protein 52.2
- Lipid 18.9
- Carbohydrate 14.8
- Ash 9.7
Source: Leger et al 1986
Not a great deal of difference wouldn't you say?
I believe that brine shrimp is a nutritious form of food for fish regardless of their stage of development, after all where does that baby brine shrimp egg sack go? It gets consumed by the brine shrimp!
I don't know where these people that say that brine shrimp aren't nutritious for fish get their information from. Do they read scientific reports, or just repeat what they've read on fish keeping forums?
I would say that over 50% protein in both baby and adult fish is pretty good!
Actually, if you look at the analysis you gave, you can see that the lipid content (fatty acids) in new born brine shrimp is approximately 40% higher than that of adults. That is a significant difference. When considering the nutritional value of brine shrimp, it refers to fatty acids and not protein (which yes you are correct, it is similar). Furthermore, you mention that "brine shrimp is a nutritious form of food for fish regardless of their stage of development, after all where does that baby brine shrimp egg sack go? It gets consumed by the brine shrimp!" Yes it is consumed by the brine shrimp but then it is BURNED through activity and what is left over is the ash content (non-burnable minerals)... which you can see is 40% higher in adults. So the nutritional content IS different between adults and newborns. Also from the same text I quoted earlier.. "brine shrimp nauplii have their greatest energy content at hatching. There is a substantial decrease in the nutritional value of nauplii between instar I (first larval stage) and instar II (begins to feed) stages, with a reduction in organic content of 24% and a decrease in lipid and energy content of 27%."
LASTLY, "Copepods are readily digested by fish larvae and are superior to rotifers and brine shrimp in terms of nutritional value."...but are difficult to mass culture.
I have worked in a lab where rotifers, brine shrimp and larval fish (salmon, cod, zebra fish) were reared. The fish were always fed instar I stage brine shrimp or enriched rotifers and adult brine shrimp.
Brine shrimp may or may not be beneficial for young fish in terms of chitin (I have not read that paper but I do have access to JSTOR so if you give me the title or authors I can try to find it - I love reading new things!); however, in terms of fatty acids they are lacking.
I hope I did not sound like a know-it-all.. I just wanted to share my sources, which are not just from "reading fish keeping forums" but have come from "real studies." I wont point any fingers but I found that some of your guy's comments were very judgmental.
Lastly, I apologize to Kremlin that his post turned into this! I hope your question has been answered
