Mantis shrimp?

Ive seen 20 gallon tanks being used to house individual Mantis shrimp so IMO a single in your 29 should work out OK

nems ? they need a very mature set up, the older and more conditioned the water is the happier they are
depending on the species they may not have enough light and the Mantis being a secretive creature in general prefers moderately lit tanks which may not suite the nem

Steve

 

I have to say no on the anemone if you get a clown mantis.

O. scyllarus (clown mantis) requires very dim blue lighting, as they occur naturally in deep water. Bright lighting is detrimental to their health, often causing shell disease.

Anemones require very bright lighting.


EDIT: Some other species would be fine with certain anemones, so long as it isn't a carpet anemone or something that is going to eat the mantis.

 

I actually wouldn't recommend a 29g cube for a scyllarus. A cube will not offer as much "floor real estate" and give you more tank height than is needed/useful. My peacock, after a few years, was much too big to fit in 29 cube. I chose a breeder so he could run around.

Whether or not one would be a good tankmate for your clowns would depend on how much you like your clowns. He will give it a go eventually. It took one of my mantis' a whole year before he killed his poor little cave mate. They slept together for that long and then one day...... nom nom nom.

 

i kept a peacock mantis (aka clown) in my 29g biocube. Bob got to be 12" before she died. They are not overly active creatures, but do require a good amount of rockwork for dens

as far as keeping an anemone, the answer I would venture is no, for 2 reasons. First, mantis are like the obsessive housewife (which is not me). They constantly "clean" their house and redecorate it. So the anemone may not be where they like it, and will try to move it, damaging and killing the nem, which would be a bad thing for the tank. Second, mantis can get shell disease from to bright of lights. Your biocube light is PERFECT for it, anything stronger will hurt the mantis.

As far as fish in the tank, I would say no to clowns. The best thing to do when/if you get a mantis is to get to learn your mantis. IF YOU can teach them that you are the food source, then you will likely be able to put certain fish in there with him. However I would say wait at least 8 months or so before putting anything in there. Mantis are also smart and will learn that food comes from you.

Fish that should not ever be placed in with a mantis are any type of bottom dwellers or any slow, stationary swimmers. Also no expensive fish that you would hate to see be ate. Even with the mantis knowing you are the food source, they might still revert back to their "natural instinct"

Corals that require low light should do fine, however remember they will redecorate their tank like they want.

Food wise, depends on the mantis. I fed Bob every other day and would consist mainly of frozen krill. About 1x a week I would toss in a turbo snail into his den for her to break apart and eat. They require iodine to molt well (krill, snails etc). DO NOT EVER DOSE IODINE....will kill your mantis in a heart beat. Plus smashers need to excercise their smashers or else they will atrophy, that is why you have to give snails

Can they break your tank, yes, it is not unheard of. Will they break your tank, I would bet my last dollar that they will not unless your tank has a crack in it, or someone is teasing the mantis. Most tanks that are shattered have someone on the outside banging on the tank. A biocube is best suited for mantis because of the rounded curves, which takes a greater force then squared corners.

 

My peacock was very active and used up every bit of space I gave him. When I moved him from a smaller tank to a larger one, he became quite a bit more active and built some very elaborate tunnels with the extra room. So, it's not that they can't fit it a 29... You'll just see a whole new mantis when given more appropriate space to move around in and build.