I've done clown loaches, they are rough to net. The trick is to wait for the tank light to go off and put some food down for them, then hit them with a flashlight and scoop them up.
I once spent almost a month trying to catch one, single, male wild X helleri (swordtail) in a 75 gallon planted. The trouble with him was he seemed to realize that I was after him, and even though all of the other swords would be busy eating and doing other stuff, he would never stray far enough from cover for me to nab him, even though I was spending hours waiting patiently by the glass. I even had him in the net a couple of times and he managed to swim upward faster than I could pull the net out of the water and got out. I finally did get him with the aforementioned flashlight trick.