I have a lot of Shubunkin/ Koi mix in my pond. One fish laid eggs and I have about 15 small guys no bigger than 4 inches long. Don't want to take them all out. I took my fish out last year for the winter. Rather not this year. What do I need to do? Do I need to run my filter and pump in the winter? Should I just let the pond freeze over and my guys will be fine? Pond is about 5 feet by 4 feet and about 1.5 feet deep. I ask now because my pond store as a huge sale one for the next few weeks so if I need a deicer or something I rather get it now on sale.