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What is DHA?
 Technical Description
Importance of PUFA/HUFA function in Finfish & Shrimp
The DHA/EPA Difference
** It is well documented that DHA rich fatty acids are required for proper larval development. Fish oils may exhibit higher EPA levels than ALGAMAC, however, through the process of retroconversion, most marine organisms can produce sufficient levels of EPA from DHA. Conversely, many types of marine animals are incapable of elongating EPA into DHA resulting in a DHA deficient diet unless supplementing with a DHA rich formula 

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Importance of PUFA/HUFA Function and Other Trace Elements in Marine Organisms (Finfish / Shrimp)       

[download pdf file - What is DHA?]  or read below
[download pdf file - PUFA-HUFA function in Marine Organism]

A Brief Synopsis of the Affects and Benefits of the Fatty Acid: DHA

The requirement for 22:6n-3 (DHA) fatty acids in marine fish and shrimp nutrition has been established by Kanazawa, Watanabe and others via feeding diets both rich and deficient in these lipids. The exact mechanism for this requirement is well documented for fish and vertebrate animals but less so for shrimp. The most likely answer may be in the postulate that biological membranes (cells) rich in di-22:6 (n-3) phosphoglycerides have a phase structure that is relatively constant in the face of changing environmental variables such as temperature, pressure and salinity and also a normal and unchanging bilayer width. These considerations rest heavily on the facts that the double bonds in naturally occurring PUFA/HUFA are methylene-interrupted in the cis orientation and that the more double bonds there are in a fatty acid, the more the fatty acid is structured by these double bonds. This effect reaches a maximum in 22:6 (n-3).

bulletThis generates the favored minimum-energy conformational "angle iron" form of the molecule. It would account for the highly beneficial effect on stress tested shrimp containing high levels of this 22:6 (n-3).


bulletA second requirement for PUFA/HUFA and 22:6 (n-3) can be found in the vitellogenic process and precursors for the enzymatic and hormonal processes within the shrimp.


bulletProduction of ecdysone for molting, growth and egg production require highly mobile and flexible energy sources as found in PUFA/HUFA.

Fish phosphoglycerides generally contain about 50% of their total fatty acids as n-3 PUFA/HUFA with a ratio of 22:6 (n-3) : 20:5 (n-3) of about 2:1. This is seen most clearly in the phosphoglycerides of fish eggs.

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The lipids of diatoms contain large quantities of 20:5 (n-3) with appreciable quantities of C16 (n-3) PUFA/HUFA but negligible amounts of 22:6 (n-3), whereas the lipids of dino-flagellates contain large amounts of 22:6 (n-3) and also 18:5 (n-3).

bulletMost hatcheries do not culture high PUFA/HUFA species of micro-algae to supply 22:6 n-3 sources to the larvae and thus the origin of substitution PUFA/HUFA to the diet of shrimp (and other marine eukaryotes) with commercial products containing high levels of these lipids.

Innumerous comparisons of oil-based enrichments vs. whole cell preparations of AlgaMac (Schizochytrium sp.) have shown that not all of the pigmentation and eye spot development of larval fish could be attributed to fatty acid composition of the larvae.

bulletWhole cell preparations of AlgaMac supply a broader profile of nutrients such as carotenoids, sterols, phosolipids and vitamins than oil-based enrichment products and may account for this observation.


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Technical Explanation:

Dososahexaenoic acid (DHA), 22:6(n-3) is one of the longest chain HUFA's in the n-3 and n-6 series of fatty acids. DHA along with DPA and EPA are long chain fatty acids essential for the normal development of larval fish and shrimp (Watanabe et al. 1978) and also oyster spat (Langdon and Waldock (1981), Ostrowski and Divakaran (1990), Watanabe (1993), and Ozkizilcik and Chu (1994). Aquaculturists derive these fatty acids mostly from fish oils (ie: Menhaden or Squid -Ika- oil) offered by many manufacturers. Though these oils do contain DHA, it is at very low, undetectable levels. They are mainly rich in EPA (eicosapentaenoic acid, 20:5n-3) which is also essential but not the only HUFA necessary. The main concern is most animals inability to elongate EPA into DHA. Studies suggest that most animals have the capability to retroconvert DHA into EPA but not the other way around. Therefore, an EPA rich oil will still leave your animals DHA deficient. This also includes enrichment of rotifers and Artemia prior to feeding your animals. (See: Nutritional Enhancement of n-3 and n-6 Fatty Acids in Rotifers and Artemia Nauplii by Feeding spray-dried Schizochytrium sp., William Barclay, OmegaTech Inc., & Sam Zeller, NutraSweet Kelco Co.)




Eicosapentaenoic acid (EPA), 20:5n-3 and docosapentaenoic acid (DPA), 22:5(n-6), are also in the category of longest chain HUFA's in the n-3 and n-6 series of fatty acids. These long chain HUFA's are integral, through biosynthesis, to early nervous system development of fish and shrimp. The n-6 HUFA, including arachidonic acid (20:4n-6) is also important as the precursor of some prosta-glandins and other biologically active compounds which regulate growth and reproductive functions (Stanley-Samuelson 1987; De Petrocellis and Di Marzo 1994). Napolitano et al. (1988). Tests suggest further that the n-6 fatty acid may be critical for normal marine bivalve development and reproduction (Napolitano et al. -1988). Again, the focus is on the ability of marine animals to retroconvert DHA into EPA/DPA and its inability to elongate EPA/DPA into DHA.

High DHA emulsions/oils vs: AlgaMac-3000
High DHA emulsions/oils may be DHA rich but like any oil, have a shelf life. Over time, the integrity of the oil will diminish and ultimately go rancid. Also, oils compromise the water quality. They are difficult to mix into the water (especially cold water), and much it ends up being wasted.
With AlgaMac-3000, you get a clean, hygeinically safe dry powder that readily mixes in water and will last on the shelf.

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General questions for Aquafauna please contact: aquafauna@aquafauna.com 


PO Box 5, Hawthorne, California 90250 USA / Tel: 310-973-5275 / Fax: 310-676-9387 

Last modified: February 18, 2016 |||   Legal Notices