Eddie,
Yes railings on both sides. What great ideas you have, but in this case I think I'll just go with a simple inexpensive approach. I'm using 2x6's as posts and mounting a 2x4 flat on top of the posts for the railing. The posts are tied into the runners/stringers and the top walkway boards so they seem to be pretty sturdy. If a person fell into a rail, they might not keep them out of the water but for adding sturdy hand-hold this looks like it will work fine. It won't be a work of art, but should make the kids and others feel more comfortable when walking across it.
Regarding the grow out pond. It is actually a little cove that has a very small wet weather creek/draw running through it. This may not work, but my plan is to use poultry wire across the base of the cove. The wire is 1 inch and I'll probably overlap it if it seems necessary, but my main objective is to keep large LMB out of this area while small 4 to 5 inch fish grow to 8 to 9 inch fish behind the fence.
The vulnerable area will be where the little creek flows through. I'm trying to remove everything such as brush/vegetation that might cause a problem and plan to put in a blocking fence above the pond to catch any debris. I also plan to use 12.5 guage fence wire anchored to deep set in concrete wood posts to help hold the entire fence in place but if something big floats down during a huge rainstorm, this fence probably won't stand up in that area where the little creek channel is. This channel is small, about 2 or 3 feet wide and 2 feet deep. It is very gently sloping so doesn't become a raging torrent even in big storms....but debris is what concerns me.
For the fish gate, I'm building a walkway out to a box in which I will place the gate. The gate will be a framed 3 foot square covered with poultry wire and will fit into slots in the box so that it can easily be raised and lowered from the walkway.
The natural wave action, winds, and any rains will provide flushing for this little area, but I don't intend to have fish in it for much longer than a month or two at a time. I guess it is best described as an experiment, but I think it has a reasonable chance of working and if it doesn't, won't be a big loss.
Got my rebuilt injector pump back on the dozer today and hope that maybe by Friday it will be dry enough to get the dozer in there to scrape everything out clean. It's an adventure.