Nice find. I'd be looking for more where that came from! Looks like a Steele's Niagara Star Bitters c. 1864-1870. It's listed in one bottle book with a value of $750-900.
Nice find and uncommon bitters. While the value mentioned may be right, bottle value is highly dependent upon condition and color. Any damage will effect value while in the same light collectors value variations in color as well. Usually amber is a common color with bitters .
Great keeper unless you need the cash. Look carefully for nics or cracks, they can greatly depreciate a bottles value. Maybe bring it to a local bottle show and get some idea of its price. Bottle clubs often have shows all over locally and nationally. Awesome find for any bottle collector, keep in a safe place where not to many people can handle it. Had a similar one and someone else dropped it and that was it!