Catching Minnows from a pond?

There is one small problem with using a trap. I have to go to a public park lake to do this. Meaning I can't set a trap and leave it for any long period of time. I might just put together a rectangular frame out of PVC and then use silicone glue to attach a nylon window screen to the frame. I could sink the contraption in shallow water, put food on top, wait for the fish, and then pull the whole thing up. Any thoughts?
 
jsut do it hillbilly style, tie a rope to the trap throw it out far in the deep along the current, tie the rope to a heavy rock then put a whole bunch of debris over it all so it isint noticed. (Sounds like I do this daily huh?) :)
 
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