i have a fresh water crab...a red claw crab i believe. his body size is the size of my thumb nail. i have had him for about four months and he has gotten a little bigger and alot darker. but lately he has not been crawling outside of the castle in his tank, except to eat. and when he does, he slow to get to the food and than doesnt move. he used to run to his food, than take it to the top of the castle to eat, its quite cute. my consern is that he may need something added to the water of that something is not right. when i move the bowl to do a water change alot of white "whispy" objects get kicked up in the water, it doesnt look like poo...but what does crab poo look like anyway. thanks

Optional Information:
Age: <1; Breed: fresh water crab...red claw?

Already Tried:
1.5 cup water changes (one gallon tank) 3x a week. changed food