Quinn,
What types of fish do you have with your shrimp?
My spotted hawkfish ate the peppermint shrimp from my 42 shortly after I added them
I suspect he also did in the pair of cleaners we also had had for quite awhile. My guess is that he started to harrass them and they took up staying near the powerhead, but he eventually got both of them one night
Someone else suggested that my yellow coris wrasse might go after shrimp too.