Is it safe to take fish oil while being on zoloft (sertraline) 200mg and valproic acid 500mg?

Yes: This is as safe as eating fish while on these- probably safer, as a good fish oil has been purified of mercury, pcb's etc. Research studies show that adding fish oil to anti-depressants like zoloft (sertraline) often result in additional benefits (though some studies disagree). Fish oil is quite safe. See http://www.Drweil.Com/drw/u/qaa400988/fish-oil-for-depression.Html.