Yes, sometimes they do that in the wild. But most of the time, the shrimp become snacks. What tank is he in and what size? You shouldn't of added the trigger, with the shrimp, because chances were that the trigger would eat it. I'm guessing the trigger is small. Thats good though, that your trigger is living succesfully with the cleaners, and letting them pick at him. But in the future, you may have to get rid of the trigger besause... 1.) You have a 25 and 32 gallon, those are two small for clown triggerfish, they get around 14 in. in the home aquarium, and around 20 in. in the wild. If you are planning on upgrading for your clown, you will need a 150 gallon or larger aquarium. 2.) The clown trigger will eventually grow big, and triggerfish learn quickly. My friend, has in his tank a clown trigeer and had a bunch of damsels. He bought the clown trigger at 2 in. and had damsels 3 in. The clown trigger, grew up with the damsels for a year and got around 6 in. and still living with the damsels. But one day, the clown trigger accidently bit, the damsel, and the damsel died. Next morning he woke up and found nothing but a clown trigger. Triggerfish, are smart, and learn quickly. So eventually it might attack the shrimp, but that probibly won't be until a long time. But that is excellent to have a triggerfish live with any invert, especially shrimp. Congrats, and keep up the goodwork.