What is the usual antifungal agent used against aspergillus niger?

Several choices. Three classes of antifungal agents are available for the treatment of invasive aspergillosis: polyenes, azoles, and echinocandins. Historically, Amphotericin B was the major antifungal drug used in patients. Currently, the drug of choice for invasive aspergillosis is voriconazole, which can be replaced with lipid formulations of Amphotericin B in intolerant patients.