Chemical warfare may not fare well with future invertebrate inhabitants. Coppersafe and similar products remain in the tank via silicone, substrate, filter media and take a while to get back to invert safe levels. Do you have a way of transferring the stuff you want to keep in the meantime, and you can nuke the tank at 120 degrees for a day. Return the keepers after the fallout. That is, if non- lethal force doesn't work first.
I also like the pea puffer idea. Wonder if your LFS will rent you a squadron. Ask if you can buy them, fatten them up, and return them later.
If all else fails, this sounds like a stellar reason/opportunity to set up another tank for the Fire Reds
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