Snowdog,
Bigger is not better with trout ponds unless it stays cold all summer up there. The smaller it is the easier it is to keep it cool in summer. However you want steep sides if possible to keep warming down and if you do choose to grow out the trout through the summmer you need to add cold aerated well water if you don't have artesian well flow.
Usually it's not winter that's the problem in temperate climates -- it summer and trying to keep summer temps below 20 C. and ample oxygen.
If thick ice is a problem in winter then keep a small area open with a diffuser and a small compressor.
I grew these beauties in a 1/10th acre pond 88 by 59 feet. Steep sided and 9 feet deep. That's small enough to keep cool with well water and large enough to have fun playing a fish.
I look like like a hard drinkin' Cunuk with a hangover in the brook trout photo eh?
Actually I just got up and it was cooooooold out there! I also have allergies and my eyes look that way when I first get up. And I'm a slob! :p
