Dave, Ric is correct on my comment that a normal stocking rate may be an "overload.When you stock it consider a 25-30% rate to start. There are many many ponds just like yours that are great little fisheries.My smallest pond is only 4/10 acre and has some 3-4 ft depth at the water source entry point(approx 20-25% this depth) and is a very nice pond.Started with 12-18 inches of muck 5 years ago and have none as of today. It is circulated with 4 diffusers due to the 38 acres of ag watershed that feeds it. It is the pond on the right side of the aerial pic on our web page.As far as winterkill from being too cold I wouldnt worry about that, as soon as you have ice cover the bottom of your pond will be for the most part the same temp as the rest of the ponds in the country with ice cover..Now as far as o2 depletion that can be different. This pond may be a candidate for a central diffuser(or 2) in the deeper area and a additional diffuser designed and placed in the shallow for additional spring summer and fall application but primarily a winter diffuser. This approach keeps the deeper water warmer in the winter as the main diffuser is shut down and all of the cfm is diverted to the shallow winter diffuser.I would also plan on running the winter diffuser most of the winter "if" you do a muck check and have 6-12 or more inches.This will allow the pond to ice over which is good (insulation) and open somewhat to let gasses out and sunlight in if snow cover persists on the ice. Like Ric stated with the tree debris you have a buildup that robs the pond of oxygen is probaby there.Decomposition takes place 24/7 >365 If you have decent dissolved oxygen then the aerobic bacteria will decompose and render your sediments to CO2 and H2O if not Anerobic bacteria will do a lousy job of decomposition and leave you with sulfur foul smelling muck. Your biological (biochemical)oxygen demand (BOD) is high and the supply is probably very low.You want just the reverse of this. If you add fish your demand is even higher so a need to address this is vital to a good fishery.This will reverse in time when you aerate.I would not consider stocking it until I had a plan to address the low O2 situation.When you do a muck check just use a rod or pole of any type that is 1 inch and covered on the end. That size snakes through muck quite easily and you will feel the resistance to the hard bottom.Once you start to feel the pole enter the muck just mark the water line and see how far down you can push.Crude but it works. I believe Bill Cody had a post on muck depth check awhile back so you may want to do a search for that. Also just stir it in the 2-3 ft depth from shore and if you can smell it dont stock it (just yet)Ted