DoDad is right, a seine net is the proper tool. As rdk said the size of the pond is not related to how easy or hard it is to catch fish with a minnow net.
Contractor said bigger is better. There's a surprise. Any chance it cost more too?
Aqua-scape ponds do need to be emptied and cleaned once a year. Pretty much impossible to clean between loose rocks any other way. I mortar rocks in place to make normal cleaning possible and get the same look. The rock bacteria thing they promote is just for people new to ponds. Sounds good and makes no actual sense. Rock gets covered in algae and dirt in about 1 day. A simple stream, waterfall or bio filter will provide much more suitable surface area.
Aqua-scape ponds are generally very shallow also. Not that great for fish. But it can get around city codes for permits and the more shallow the water the clearer it will always appear.
It's common knowledge that larger ponds are easier to maintain or stay "balanced" better. But common knowledge, while often cited, is rarely right. A 15,000 sf home is easier to maintain than a 500 sf apartment because the crap in the large home is spread out. Three dirty dishes in a small apartment makes the place look like a dump. I had a converted swimming pool once that was zero maintenance for 4 years, right up until huge mats of crap started floating to the surface. Then it was quite the little nightmare.
Later I had a
30 gal pond that I cleaned with a minnow net. Easiest pond I ever kept, cleanest too. So it kind of depends on how you plan on maintaining the pond. If you're willing to let the crap pile up then yes, bigger is better. If you plan on weekly or monthly cleaning then smaller is easier. Not saying one or the other is better, just different types of ponds and ponders.
Since your contractor says a larger pond is easier to maintain I assume he'll charge less for the annual cleaning? Ask him this while he's drinking coffee, but stand to the side. Very entertaining.
Size should be determined by what you want. You want to raise show Koi, a water garden with a few goldfish, or just a landscape feature. Aqua-scape ponds are nice landscape features for people with the means and desire to hire out the build and maintenance. They're nice to look at through a dinning room window. Not really a good choice for someone who wants to be hands on.
If pond keeping is a hobby for you it's best to start small and simple. You will learn tons and be able to make a better decision later. I would say all ponders who like the hobby will always want a bigger or more ponds. Just like any hobby. We will also also see where improvements can be made so we generally like to change stuff. When you spend $10-30K on a professionally made pond you can kind of lose that ability to make changes. Unless you are very wealthy most people will never rip out an expensive pond.
Aqua-scape ponds are great landscape features. Nothing wrong with that. But I've never heard of a pond hobbyist who replaced a Koi pond or water garden with an Aqua-scape pond although I assume Aqua-scape would disagree. Just different things.
