Six lines are fine. You just have to set up the tank properly to keep them. They are constantly foraging for food hovering over the rocks, stopping, looking, darting in, out, and eating all along the way. If the tank isn't as mature nor has a lot of coral and algae covering the rocks it makes it a bit more difficult to simulate their natural environment. This clearly isn't helping you, right?
To catch it - as many already suggested a fish trap with some tasty food should do the trick. However, you have to be patient and give it a couple days. It isn't going to happen over night. A clear plastic soda or water bottle with the top cut off, and inverted, usually work. You cut the cap and neck off, flip it over, secure, fill with tank water, place a cube of food or something really good like LRS frozen, and put it near a rock. Don't forget to attach a fishing line to it so you can pull once it enters. The key is to not set it right away. Put the food in so it can enter and exit safely. Once it does this then set the line and food - you will be good.
I just captured a lavender tang using this method and it took 3 days. It also helps to reduce feeding if not all feeding so it will be more hungry and prone to enter. If this fails then your only choice will be to remove corals, rocks, and even water to safely net. This falls into the re-homing of fish not properly sized for the tank

Yes, you can rehome. However, you first have to catch it...
Great fish with proper environment. Similar to damsels. If you want a wrasse a yellow coris is a good choice. You want something unique you can go for a possum although you may not see it every day.