It sounds like you have already done a lot of excellent prep work on your pond.
Yes, you can definitely make a 1/2-acre pond that is 9-10 feet into a very good fishery.
1.) Generally, trees on the dam are a big no-no. However, those are some well-established trees. Clearing them now might actually cause some leaks as the roots rot out. (That might be a good separate question to post and get some expert advice just on that topic.)
A few of the cottonwoods are dead/dying, so any issues with the roots may show themselves in the coming years.
2.) I don't see an obvious waterway entering the pond, or an obvious outlet. Are there just gentle slopes delivering water into the pond? If there is no outlet structure, is there any evidence of erosion damage where a flood caused the water level to overtop the dam? That would be a priority to "fix" prior to spending money on fish.
The pond sits in a bowl with runoff from the surrounding area feeding into it. I believe there is a spillway on the end of the dam that my neighbor owns. I don't know if there is rip rap or a pipe over there. Kind of an odd situation with him so I haven't been over there to check in person. When cleaning out all of the underbrush behind the dam I did discover a concrete pipe sticking vertically out of the ground at the base of the dam. It's about 6" diameter. There's standing water in it a couple of feet down, and probing with a stick it seems to be full of mud. I don't know if it has anything to do with the pond or not. I don't see any evidence of a stand pipe on the surface of the pond. At first I thought it may have been an old well, but I doubt it would have survived construction of the pond. So I'm guessing it's related to the pond in some way..
3.) How far away is an outlet for 120V electricity on your property? Aeration would help your fish during the summer, since the trees are going to reduce wind action to naturally aerate the water. Also, aeration would aid some aerobic bacteria in eating up some of your muck.
It's several hundred feet to the house. If absolutely necessary I could run power there in the future, but would kind of like to see how things work out with the pond and the neighbors before I go too crazy on expense and labor. Are there any chemicals or something that can help with the muck/leaves?
4.) What type of fish would you enjoy? A largemouth bass - bluegill pond would not be that expensive to create or maintain at your location. However, there are lots of Missouri members that have other fish ecosystems.
Bass and bluegill would be fine, maybe a few catfish as well just for a change of pace and fishing style for kids.
5.) If there is no obvious waterway to the pond, there is a chance that a drought took the pond to a very low level or dry and killed off the previous fish population. Has the pond stayed mostly full the last few years while you lived there? If so, then you should be fairly low risk moving forward with your development plans.
In the 4 years we've had the place I've not seen the pond level fluctuate more than a foot or two. That's not to say a drought may not have done the damage before we got here. I was guessing that maybe the pond had gotten too brackish from muck and leaf litter and that changed the water chemistry to where it wouldn't sustain fish? The frogs and crawdads are thriving though.
Good luck on your new pond project! There looks to be lots of excellent potential to my eye.
