Aquaponics Digest - Sun 11/28/99
Message 1: unsubscribe
from Patricia Ladipo
Message 2: Fw: Greenwater Culture in Israel.
from "TGTX"
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Subject: unsubscribe
From: Patricia Ladipo
Date: Fri, 26 Nov 1999 20:06:26 -0500
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Subject: Fw: Greenwater Culture in Israel.
From: "TGTX"
Date: Sun, 28 Nov 1999 16:26:12 -0600
Thought I would post this question to the aquaponics group as well
(I originally posted this on tilapia@onelist.com). If anyone can help with
some of these questions I would appreciate it.
> Dear Mr. Snir:
>
> I would very much like to hear from any Israeli Tilapia farmers on the
> fundamentals of greenwater Tilapia culture as it is practiced in Israel.
> Specifically, I have questions about the following:
>
> 1) How protein content (%) in feed pellets may be lowered in greenwater
> culture, and in what manner (in stages or degrees, or at all growth
stages)
> to take advantage of the algae & suspended bacteria food source and the
> algae-heterotrophic bacteria function of assimilating nitrogenous waste
into
> their biomass.
>
> 2) Are specific species of unicellular green microalgae used in periodic
> innoculations of the culture water, as algae blooms develop exponentially,
> then crash? If so, what specific algal species have Israeli Tilapia
farmers
> found best vis a vis water quality management and Tilapia nutrition and
> harvest yield?
>
> 3) Any problems with undesirable algal species dominating the culture
water,
> such as Anabaena sp. (blue-green algae) or others, due to N/P ratios or
C/N
> ratios, or other factors?
>
> 3) Are you aware of any compositional analysis having been performed on
> those beneficial algal species in vivo, that would aid in nutritional
input
> analysis for the Tilapia? I am especially interested in any work on
> essential fatty acids (EFAs), highly unsaturated fatty acids (HUFAs), and
> DHA coming from the algae grown in greenwater Tilapia culture.
>
> 4) I dimly recall some carbon isotope studies of greenwater Tilapia
culture
> conducted (I believe) in Israel, indicating that approximately half of the
> assimilated carbon that went into the fish came from the artificial
pellet,
> whereas the other half orginated from photosynthate carbon and possibly
> recycled ambient carbon sources from heterotrophic bacterial biomass...can
> anyone cite those specific journal articles in the primary literature? I
am
> sure I must have read them in the library or had them in my office at one
> time, but it appears I have misplaced the references.
>
> Thank you very much for any assistance you may provide in this area.
>
> Sincerely,
>
> Ted Ground
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