Fisons rhymes with:
horizon's, horizons, arkansans, artisans, citizen's, citizens, citizens', cousin's, cousins, couzens, cozzens, denizens, dozens, gazans, horizon's, horizons, imprisons, kansan's, kansans, kansans', partisans, poisons, prison's, prisons, raisins, reasons, resins, rosen's, season's, seasons, susan's, telxon's
Fisons sounds like:
facing, facings, faking, fasching, fashion's, fashioning, fashions, fausnaugh, faxing, feagans, feagins, feigning, figgins, fijians, fishing, fixing, fixings, focusing, fosamax, fosnaugh, foxman's, fucking, fujisankei, fukunaga, fusing, fussing