Absorbtion of minerals by freshwater fish

[Gir234affe]

I am performing some experiments for my advanced biology 
concerning the affects of some selected additives upon the 
circulatory rates of goldfish. In order to begin the primary designing 
of the experiment, I need to know in what form these substances 
are typically absorbed. At this point in the experiment, I am hoping 
to test calcium and vitamin A. If anyone know the form in which 
these substances are absorbed, I would greatly appreciate this 
information.  


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