Peppermint (Mentha x piperita) is on the UNSAFE list.
Spearmint (Mentha spicata) is safe.
Catnip (Nepeta, aka Cat Mint, Field Balm) is on the unsafe list but I had often questioned this for two reasons: 1) no explanation is ever given as to why a food has a negative rating, 2) other plants in the mint family are safe, 3) insects did not avoid it. When I found catnip growing wild on the ranch where I harvest for Crabotanicals, I wanted to conduct a food trial on it to satisfy my doubts. I put into the tank a flowering top complete with seeds, blossom, and some leaves which I was careful to bruise since the fresh oil is said to attract cats. The hermit crabs did not avoid the plant, but certainly did not eat any of it. So, there is not enough evidence to overturn the unsafe rating—especially since more conclusive evidence might have landed it on the unsafe list to begin with.