I doubt that the mantis trap will work. *It's too small and confining for a fish to feel comfortable going into it and the fact that it's opaque doesn't help things either. *You can make your own fish trap easily.
Take a small pop or water bottle (they are a handy, multi-purpose tool in my house) *

*Cut the top of the bottle off (about 2-3 inches from the top). *Clean both halves of the bottle well with diluted vinegar. *Then fill the bottom half with tank water, put in some type of sinking food and push the top half of the bottle into the bottom half so that the opening of the bottle faces down, towards the bottom of the second half. *The fish get in but they don't get out

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