Mantis Shrimp

I've lost 6 fish that were kept with my mantis. 100% positive they were dinner to my peacock.

 

Your sarcasm isn't lost on me and it's not appreciated. I will, however, answer your question without such because, as you point out, misinformation is everywhere. I've seen someone write "You can keep a panther grouper with damsels because I've done it." Just because one person has success keeping a certain combination of things together, doesn't mean everyone can or anyone should.

There are many species of mantis shrimp and some will kill fish, some will kill crustaceans, some will rearrange rock, some will be relatively harmless, some may even break glass.

On the the question:

Yes, I'm sure it was not filtration or other techniques from 15 years ago. They are effectively the same I use today - live rock/sand and protein skimmer.

The reason I'm sure it was him was that I saw him devouring a Royal Gramma and Flame Hawk on two different occasions. After removing him I didn't lose another fish until I broke my tank down in the mid-2000s, about seven years later. No, I don't think it was the filtration.

I'm sure a fish eating mantis will do fine with certain types of fish and non-fish eating varieties may kill some fish. What I know is that I lost at least half a dozen to one.

Some quotes from around the web:

Aquatic Community: A common way to discover that a mantis shrimp has been introduced is actually that fish and other reef life start disappearing from the tank.

AllTropicalFish.com: Fish, crustaceans, molluscs, aquarist's fingers(!), all can fall foul of this voracious hunter.

Practical Fish Keeping: 'Spearers' have rapier-like appendages often with barbed tips or serrated edges which impale or clasp and disembowel prey. Such species are typically ambush predators that lurk in burrows made in soft substrates and feed on soft-bodied prey, including fish.

An interesting article where Dr Roy Caldwell talks about different species of mantis shrimp, including the fact that he has had some break glass while in his care.

Quality Marine: If you find yourself with an unwanted mantis, it is probably because you keep finding dead fish or hermit crabs. Worse yet, you might have experienced a broken tank or a wounded finger.

And lastly, I still remember seeing a special on them on TV a number of years ago where they showed a fully grown Queen Angel taken down by a mantis not even a 10th its size - and showed one breaking glass.

 

Any luck yet? Me pulling out every rock was only plausable because I was still cycling at the time and nothing was in my tank. It sucked but gotta do what you gotta do sometimes..

Make sure you have the right rock because my Mantis had two different spots it liked to chill...