Finntastic
Aquarium Advice Addict
Yea mantis shrimp don't play well with others, hopefully he wasn't aware he had the mantis shrimp. They are extremely finicky eaters and most do not eat right away. You would need to make sure the fish ate before purchase. Most eat pods and rotifers. The feeding habits is where the "expert" comes in. They are also very small and slender and can easily slip through overflow boxes, powerheads, and anywhere else for matter. They are hardy if you get one eating and is a peaceful tank (no bullies). I wouldn't recommend it as a first saltwater fish for sure. They do great in seahorse and pipefish tanks though, which is all "expert" as well. They are not super likely to jump but they do cling on to stuff.
My friend didn't know he had the mantis shrimp at the time. When he realized he had mantis shrimp he tried to get rid of them. When he finally got them all out it was a grand total of nine shrimp caught (mostly peacocks but there were two black mantis shrimp as well) and 5 fish gone including a 4" Diamond goby all were mantis food. Now we tease each other about his mantis shrimp infestation and my bristleworm infestation.