I had a true pygmy octo for a good while.
#1. They only come out at night it doesnt matter if you feed it or not in the day it will wait until night time.
#2 You need high salinity because they are purely fleshy and have a higher surface area.
#3. They do not like light at all.
#4. They like colder and cleaner water then most other fish.
#5. A trigger will try to eat it, or the octo will try to it the trigger, which ever gets hungry first.
#6. Keep octos alone they do much better that way
#7. THEY LIKE CLEAN WATER
#8. They are VERY short lived. VERY
I hope this helped you you can check out what i got up about mine i didnt get a chance to finish it nor will i probably ever because she has passes away.
http://www.geocities.com/djmd04/