Intelligent creatures.

Once a every week or two should be enough. There is a lot of conflicting information about the smashers atrophying, mine was constantly banging away at the rocks in the fuge.
No clue on lifespan, hopefully someone more knowledgeable can chime in. Lighting definitely doesnt need to be super intense, PC's should be fine. Might look in to a used AIO cube tank to house a small species(smithii, wennerae or viridis) but would probably want to go with something beefier if you are considering keeping a peacock. Not sure what the minimum tank would be, but they get to be a pretty big size.

 

I have a 37 gallon now.. but its a 37 deep.. and its thin glass...
I will definately do acrylic if I go with a mantis.. I like the peacock mantis.

 

I am going to go out on a limb here....I know people are going to come back on and say "you are wrong..." BUT....

I think the tank you currently have would be fine if you were to get a peacock mantis. Though it can happen, it is VERY VERY unlikely that they will smack the glass and break it.

Tanks that are more bowed are stronger then square or rectangle tanks....

I have Bob in a 29g Biocube and have never been afraid that she will crash it. I have in the tank for her probably 20-25lbs rocks, and 2 large PVC tubes for her to hide in. I placed the tubes and made dens with the rocks around it. I also have corals in there and she is moving them around now (just went into another bad molt..upside down etc)

Lightwise you do not want strong lighting in there...just pc or T5 lights. They can get shell disease easier with higher amt of lights.

I feed her a turbo snail a couple times a month. Sometimes more, sometimes less. I keep turbos in there and she doesnt bother them...unless she gets really hungry or if I drop them in the den.

I would not recommend an octupus...they are too intelligent and you would have to get a secure cover, do enrichment programs, etc. Too many escape and die in the home aquarium. One of the large aquariums had a major flood cause their octopus took apart its tank and drained several thousands gallon of water on the floor...and they had enrichment programs. I have also heard of an aquarium that kept having fish missing in tanks around it. They thought someone was stealing them, set up video and found that they octopus was crawling into the other tanks, eating, and going home!

 

Wow thats crazy.. yeah octo is too smart i believe.
Thanks for the input. I am selling the tank I have just because it is too elaborate I believe for a mantis and I need lights for the 125g.

If i decide to do it I will buy a smaller acrylic tank.