The trapping season for Fisher is Nov. 20 - Dec. 31. Season limit is 4. I know this doesn't help you now. You could try a licensed Nuisance Wild Control person. The DEEP website (Wildlife Page) has a list of NWCO's throughout the state or contact our wildlife division (860-424-3011), they have a list of them and/or may have some other suggestions to get rid of it. Fishers can be very aggressive so be careful. Firearms including air/pellet rifles, bows of any type, basically anything other than trapping during the season is prohibited. Should they attack unprovoked, do what you have to do to protect yourself and your kids. Hopefully it is just passing through.
http://www.ct.gov/deep/cwp/view.asp?a=2723&q=325944&deepNav_GID=1655