Very interesting! Thank you for pointing out that pistol shrimp may indeed be capable of cracking glass aquaria, which is something that home hobbyists often regard has merely an “urban aquarium legend,” so to speak.
On occasion, the pistol shrimp can present a danger to their tankmates as well as to the tanks they are kept in.
The concussion from the shock wave they produce with their pistol shots can indeed stun and kill small fish and invertebrates. Pistol shrimp are quite territorial towards other shrimp, in particular, and are very protective of their burrows. They are quite capable of killing cleaner shrimp and peppermint shrimp such as Lysmata wurdemanni and Lysmata amboinensis that are much larger than themselves from a short distance by the concussions their powerful pistol shots generate, which cause internal injuries, as I have personally witnessed on more than one occasion.
The concussion from the shock wave they produce with their pistol shots can easily kill small fish and invertebrates. Pistol shrimp are quite territorial towards other shrimp, and it is therefore small live shrimp that are at the greatest risk of running afoul of a pistol shrimp in the aquarium. For example, they are quite capable of killing cleaner shrimp and peppermint shrimp such as Lysmata wurdemanni and Lysmata amboinensis.
In general, however, pistol shrimp often do well with large seahorses in my experience, especially when they have a watchman goby living in the same burrow with them. I would never trust them with dwarf seahorses (Hippocampus zosterae) but the larger breeds such as Mustangs and Sunbursts (H. erectus) usually coexist with pistol shrimp very well. They are too large to be considered potential prey by the pistol shrimp so the little sharpshooters are generally quite content simply to clean up their leftover Mysis.
I would hesitate to introduce decorative shrimp to an aquarium with the pistol shrimp, but in my experience, seahorses and pistol shrimp most often merely ignore one another. But a pistol shrimp has the potential to kill or injure even large seahorses, and pistol shrimp almost invariably find their way into a seahorse setup as an unwanted hitchhiker on a piece of live rock.
The moral is that seahorse keepers are well advised to avoid pistol shrimp and mantis shrimp at all costs.
Pete Giwojna, Ocean Rider Tech Support