Ok, I devised a way to catch one fish out of 10, in a 75g long tank with substrate, rocks and artificial plants. Not to mention a canister and HOB filters.
I thought long and hard on this and when I went to catch the female with a mouth full of eggs it took less than a minute.
Originally, I was going top make a net that was the size of the tank's ends. It would be a dividing wall I could put in the tank and move it toward the end and reduce the area to catch the fish. Then I thought, what about making two rectangle nets the together would make a wall, that I again could work the target fish toward the end and then catch her.
Well, I did not do that. I took two butterfly nets I got from Dollartree (My favorite store on the planet) and removed the handles. Each net is about 10" in diameter. I took one in each hand and I was able to corner the fish in the middle of the tank and push one net toward the front of the glass and catch her. Normally, the fish would dart away from the net and there would be an intense chase, but I was able to use the second net controlled by me other hand and keep her from darting away. Once I had her in the net with it pressed against the front glass, I just slid the second net between the first net and the front glass. I was then able to carefully raise her out of the water and into my new nursery tank.
I hope that made sense.