Just a note on what happens to a pond without fish...My 1/4 acre pond was stocked with minnows only for the first year and the amount of frogs/tadpoles/snakes/turtles/bugs/crawdads that filled the pond up was scary amazing (basically the critters that fish tend to eat/control). Now, with predator fish in the pond, the over populations of small critters is greatly reduced.
You should consider embracing some fish life as part of the balance. Mostly, the worst that could happen is your pond ends up with a population of "smaller than usual" BG and/or LMB. Heck, even check into the HBG and HSB route (less reproduction).
If a fishless pond is very important to you, you can expect to produce an environment that will thrive with the smaller creatures and that could be truly exciting too (if you don't mind the potential exoduses that can occur as young critters leave the pond to explore their options or the amount of mammals (raccons) that may come to the pond for small critter meals) .
If your pond is getting fish from the water the feeds into it OR they are swimming up from below the drain pipe, then your fishless pond dream will be a struggle. You may have no choice but to embrace the fish and do what you can to manage them. If your pond was dry (meaning no puddles) for a month...the only fish that I know of that might carry through would be from the catfish families and they still need ample wet mud and preferably in the cooler/colder seasons.
Catch some of these fish, put them in a jar, photo them and let's see what you are dealing with...minnows would be a good part of a small creatures environment.
Your project sounds very cool btw!
