i got my octopus, mac, three days ago. the first day it was fine, coasted along the bottom of the tank and explored. it wasn't until the next day that i could not locate mac. since i live in central NY, i don't have fiddler crabs handy, and mac's body size is no bigger than half an inch (arm to arm is 3.5 inches). instead, i placed some shrimp in the tank, the first nite he seemd to go over it and eat a little, then she shot up into one of the porous rocks in its aquarium (the aquarium i have right now is a 20 gallon). the next day when i couldn't find him for nearly 10 hours i surveyed the rock he was last in, and yet no mac. i began to worry that he had died, for fear my heater wasn't working right, i checked it and it said 77 degrees. no harm there. so next i took a mirror and placed it under the filter grate of the tank just in case he was under there. success! i found him in the corner, so now i knew i had to remove the grate but be carefull not to let the rock fall on top of mac. every time i moved rocks (in a location far away from him) i would check the mirror and see where he was to make sure i don't remove rock across the surface he was under. after doin' this for about 40 minutes, i was able to remove the floor filder, ensuring that mac wasn't in the way. when he was near the front of the tank below the edge of the filter floor that i was lifting (sealed to the side so that the few stone left wouldn't fall on mac) i had my friend shine a dull flash light at him to make him move to the opposite side. he did and i restored the bottom of the tank, but now i needed to get a new filter that wouldn't trap him under the floor again. i figured the reason he hid there in the first place was that he wasn't fully acclimated to the aquarium and there was an excess of light that nite. so after that, mac stayed in the corner of the tank, really still... bright red (angry). i covered the aquarium up with towels so that it was dark and he eventually began to move about. i checked on him every 2-3 hours, checking the temperature and his activity. the temp kep fluctuating between 75 and 78. the next morning he was good, still don't know if he had eaten anything and by that afternoon he was sleeping on the side of the rock flush white, whiter than the rock... which i was assured is natural for when they sleep. that nite he was not there, the aquarium is sealed off tight and i checked the area around it-no sign of mac on the floor or there about. but that was 20 hours ago, i only check every 2-3 hours so it is possible for him to have come out, but i am still worried. tomorrow i will see if i can't get small hermit craps and snails for him. i pray to god that he is ok and just frighten. but in the back of my head i can't help but feel as if he has died in some small crevice un the rock and that i won't realize that until next week when there is still no sign of life. what should i do, is this normal? will it be ok? any suggestions? here are my tank stats aquarium 20 gallons SG 1.023 temp 77 degrees nitrate low (not sure) amonia low (not sure) filter protein skimmer, amonia/nitrate filter, water filter for marine aquariums. if there is anything else you want to know, e-mail me firstname.lastname@example.org or my aol, XAETUS i am extremely desperate, and do not want him to die.