Fishing knife for rivers and streams....
I think a SAK similar to my Adventurer is quite useful. The One Handed Trekker would also be quite useful. Your choice whether you want the main blade serrated or plain edge. I prefer the plain edge. You seldom need any serious tools when fishing, but there are times you do need a screw driver, tweezers (got to have the tweezers), awl comes in handy at times, and a few other swiss tools. For me, the blade is seldom used for cutting line unless it is major surgery. Clippers work best for this purpose. A SAK Farmer would also be useful.
Your Spydie Moran is a great little knife.
A small fixed blade... neck knife would be useful and handy to get to which is where I would go with a fixed blade versus a folder. I would prefer a kydex sheath since I do sometimes "fall in" slipping on rocks and so forth. The Dozier Canoe comes to mind as a great choice and not real expensive for a custom. If off the beaten trail a lot, I would tend to want a larger fixed blade with me, but it would almost never be used.