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Re: foods and feeding

On 4 Jul 2001, at 14:13, Rjga at aol_com wrote:

> Tyrone is not quite correct. 

I will accept that much...

> In general (and this applies mostly to 
> insectivorous fishes like killies), the best food is about 50-50 lipid and 
> protein. 

Nothing wrong with that ratio nutrionally but if we fed 
out fish 50/50 processed proteina nd fat they would be 
dead the next day. Depending on the diet of the fish and 
how its gut had addapted to deal with that need the 
fibre content is very NB. Fish that live off tiny 
crustaceans and insects(eg. daphnia, flys, shrimp etc..) 
need high fibre or their guts get septic and the fish 
die. As killies love insects, daphnia etc... we must 
assume they need some fibre. Infact the more fibre the 
less protein and lipis the better. They will just have 
to eat more daphnia however...

> Carbs are pretty useless to fish as is fiber 

I know of only two organims that lack the glycolytic 
pathway so disabling them to metabolise glucose or any 
other carb and they are both bacteria.

>, and they get all they 
> need along with insects and/or other invertebrates. Fats and lipids are the 
> same thing, except that fats have their carbon to carbon bonds fully 
> saturated (filled with hydrogen atoms) whereas lipids retain some double 
> bonds and by definition are not saturated. 

A four carbon fully saturated lipid will be a fluid as a 
20 carbon HUFA. There is a difference METABOLICLY. A fat 
(ie. a lipid that is solid at room temp) will not be 
metabolized by a fish as it would just past right 
through or worse yet get absorbed and cause all types of 
damage if it is imcorporated into the plasma membranes. 
A fish's metabolism is shaped to handle oils ie. those 
lipids that are soluble at room, or in this case fish, 
temperatures.

Finaly the definition of a lipid is as follows: Water 
insoluble molecules organic compounds found in 
biological systems. Fat and oils are part of this large 
group and are generally refered to as Fatty Acids with 
the genral formula R-COOH. Lipids are iether hydrophobic 
or amphipahtic. The issue of double bonds does not 
feature anywhere in the definition.

With all due respect (ie: I know you are way cleverer 
then me) Dr. Goldstein I think you have to revise your 
lipid biochemistry.

Bye




Tyrone Genade
Southern African Killifish Society Coastal & Offshore Coordinator
AKA 08248
tyronegenade at yahoo_com
http://www.geocities.com/tyronegenade

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