Catching fish in a large tank is a skill! A larger net is a MUST HAVE. What works for me is to remove as many decorations as possible. Then use the net to scoot everyone over to one side, towards the front corner, then swoop up the net to the top of the water. Danios will frequently zoom to the top when you try to catch them, and usually this will capture a few at a time. 'Course they hide behind uplift tubes and everything else. I'm not coordinated enough to use 2 nets! LOL! I had 2 buenos airies tetras that I could not catch until I had drained the water from my 55 gal. (I was moving it across the room). When they were flopping on the gravel it was easy!