If they're selling RES up there, ask them if they keep any over the winter, and what size pond (area and depth) they keep them in. If their pond that they overwinter them in is similar to yours, then I think you're good to go with the RES.

www.hoosierpondpros.com

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http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).