no one witnessed, our trustable lfs, in the tank wtih arrow crabs and peppermint shrimp is only chitons and snails(where she lost snails too, but turbos can and do die daily), and something was killing the shrimp until she moved the crabs to their own tank,adn i have read from several resoources to use caution, because they supposedly will eat ............even smaller fish
but then again i have also heard from others, that they have had no problems(which was also mentioned), but they are sure to keep theirs fed(as i have also mentioned), and if you'd like you can pick up almost any book and read about their diet which includes..(several things)... even small fish,
as for yours, and natural deaths(you assume???, because nothing else in your tank is aggressive enough???), i see 2 possibilities, the clown maybe(depending on the species) especially if he'd been confronted and the other arrow is another possibility, i have no idea what ele you may have, i mean even my tank has the potential, and the most aggressive thing i have is a 1.5 inch percula, but i do have lr, which means i have the potential to have a mantis, i haven't seen ay traces yet but that does not mean a thing, they are good hiders and can stay undetected for over a year especially if there is a good enough supply of food for them so they don't terrorize the tank
besides i believe i said, "that they are unpredictable and will eat almost anythign they CAN"(not they eat everything in the tank) and "some people get lucky", and i also said that they "have the POTENTIAL" (which means they have the ability), i never once said they ALWAYS DO, i just tried to keep it short instead of writing a 5000 word essay on the arrows diet and captive behaviors
by trustable lfs, i mean the one that i can trust and has so far given me alot of good advice(forget the other clown down the road), she helped us to straighten out a lot of things when we first started, wher as the other clown kept trying to sell me something else which never worked
now as debates go we have 2 for and 2 against, that is about normal for alot of things, esp. when it comes to opinions on species,LOL