zigzag is lying on the bottom of his tank next to the decoration all day. he's breathing but he doesn't want to come out, even offered food. usually he'll eat all he can immediately. seems to be hiding (usually he is very active and not shy) or sick? he's in a cycled 5 gallon tank w/filter, heater, light, plants and i tested the water parameters and they are all normal, water doesn't need to be changed. he's been in the tank about 9 months. he seemed fine yesterday, fins looked fine then, no spots dots or nothing weird that i noticed. can't really tell today because he's laying down up against the decoration...the only thing new is we put in a snail last week to help clean the algae in the tank - it's about 5 feet to the side of a bright window so it does get a bit dirty. the light is off and we're trying to let him be in case something just scared him. could it be the snail? any ideas?