I have been trying to keep hammer in my nano for a few months now. My brother has hammer growing like weeds in his tank and has given me a few heads for mine. When I acclimate them they are happy. I place them in the tank, still happy. I have awoke to the hammer being on the bottom of the tank upside down from a snail or crab knocking it over every time I put it in the tank. This go around I thought I had it pretty secure but it still got knocked over. So I used some reef epoxy and stuck it to the rocks. Well ever since it will not open and acts like its going to die off. I have it mid level in the tank, plenty of light, water flow is good. Im not sure what I can do to make it happy again.