to trap a fish, the last post left out a few details.
use a 2 litter soda bottle, cut off the top 1/4 and invert the "cone" and attach it to the other 3/4 end of the bottle. You now have a funnel at one end and I use zip ties to lock it in place. The fish will swim into the funnel to get to the bait and not be smart enough to swim out. The funnel opening needs to be "opened" up a bit so the target fish can swim in. If it is a flat fish like a tang, the opening should be shaped like a thin oval. Leave the bottle in there a few days, I use magnets to hold it against the glass for easy access. Always leave food bait inside the trap, you'll get the confident fish swimming back and forth for a while, just leave them be, till your target is in.