Mantis shrimp propagation? – 9/24/07
Hi Crew,
While doing some rearranging in my tank, I found and caught a 3 inch mantis shrimp. I thought it was lucky that I caught him, supposing he was the reason I never saw my peppermint shrimp again after the day I put them in.
<Perhaps>
While I was rearranging, I put some live rock in a 10 gallon quarantine tank I have. When I moved that rock back to my reef tank, I noticed what I thought was a very big 'pod in the q-tank. Looking closer, I saw that it was actually another mantis shrimp, only very small (maybe 3/4 of an inch). So now I'm worried that I have an actively reproducing population of mantis shrimp in my tank. Is that likely?
<Mmm, no... Much more probable is that these are introductions from the live rock>
I was under the impression that these animals were territorial.
<Are>
It's only a 55. Reading on-line I found some documents stating that the densest populations of mantis shrimp in the seas consist of 1 shrimp per square meter. On the other hand, I haven't added any rock in the last 8 months or so, so I thought it was unlikely that I could have a mantis that small that wasn't hatched in my system. Have you all heard of a captive system with reproducing mantis shrimp?
<Very rare... some smaller species... Bob Fenner>
Thanks,
Mike

Baby Mantis
Dear WWM Crew,
<Hi, MikeD here>
I recently found 3 tiny Mantis Shrimp while removing seaweed remnants from my 437 gallon tank following a feeding.  They were about the size of a Gammarus or Mysid shrimp.  My tank has been in operation since June, 2003.  Six or seven months ago I removed 2 adult, tan colored Mantis Shrimp which I found living in my live rock.<The question that begs to be asked is how large were they and why did you remove them?>
My questions are:
1. Do Mantis Fry have any natural predators?<Many, anything that will eat any other crustacean of similar size, particularly wrasses and pistol shrimp>  I have (3 angels) a Majestic, Asfur and Blue Faced Angel in that tank in addition to a large Copperband Butterfly, 12 Green Chromis, a mated pair of True Perculas, a Red Sea Wrasse, a Blue Neon Goby and a large Cleaner Shrimp.  Would any of these fish eat these small Mantis Shrimp?<the wrasse would be the one most likely, although any of the others large enough wouldn't pass up the opportunity if they catch them in the open>  
2. Should I assume that I still have a pair of adult Mantis Shrimp in my tank or could eggs have been in my tank or sump waiting till now to hatch?<My guess is that these babies may be a different, smaller species that came in as hitch-hikers in the LR, although they could also be young of the pair that you removed. In most the eggs are carried beneath the tail in normal shrimp fashion and when released become free swimming planktonic fry that are gobbled up by the fish and filter>
3. How many baby Mantis Shrimp could I possibly have inherited?<Only a couple hundred to a thousand or so, depending upon the species **grin**  I strongly doubt that many more than those you have found have survived though. There's also the possibility that what you are seeing are something else, as many small crustaceans, including some Gammarus relatives also have mantis-like grasping claws>
4. If my current marine population will not eradicate them from my tank, what would by your recommended plan of action in removing them from my tank?<A narrow necked bottle with some meaty food in it, placed top up and at a 45 degree angle near the known lair at night often works well.  Keep in mind that there are many, many species, some never growing more than 1/2" or so that function quite well as scavengers in larger tanks such as yours>  
Once again thank you for your help.
Ron

Re: Baby Mantis Shrimp in My tank
Hi Mike D,
<Hi back, MikeD here again>
Thanks for taking the time to answer my question concerning 3 tiny Mantis Shrimp that I found in my 437 gallon tank.<You're very welcome>  You asked how large the two adult Mantis Shrimp were that I had remover about 6 months ago.  One was about 2 inches long and the other was about 2 1/2 inches.<OK. Many people aren't aware that there are hundreds of different species of two types, smashers and spearers, that range from 1/4" up to a giant nearly 18" long.>  
I brought them to a local pet shop and gave them to the owner who put them in a separate tank and told me that some people like to keep them as pets in a species tank.<They do, myself included.>  I however felt that they would cause harm to my smaller fish.<The "spearer" type, yes, while the "smashers", such as the Peacock mantis shrimp generally leave most fish alone, preying on snails, clams, crabs, shrimp and any other sessile invertebrate that they come across.>  
The three smaller ones that I recently caught were identified, after inspection under a magnifying glass, as Mantis Shrimp by two different local pet shop owners.<I've learned to be wary of ID's, even by experts. Here in Florida I worked  for the city as a volunteer snake and exotic animal remover for over 10 years, and out of 137 calls concerning pygmy rattlesnakes, many ID'd by "experts", NONE were pygmy rattlers. On the other hand, I've seen piranhas mixed in with silver dollars and deadly scorpion species listed as harmless offered for sale in many LFS and even have a Stonefish, the most venomous fish known that was purchased as a scorpionfish and two waspfish that have also caused human fatalities that were sold as "butterfly gobies".>  
Thank you again for your quick response to my question.<You're very welcome, and as long as your happy with your decision, that's all that matters.>
Ron