Guppies nipping Cory

[guppypups]

So I've had a cory catfish living with my guppies for almost a year, although I know his previous owners had him for quite some time so its likely that he is very old. He stopped being quite as active for a few days, and now all of a sudden my guppies are biting him! And he's not swimming away! Should I move him to a bucket (I don't have a quarantine tank) or into my other tank or leave him be?
He swims little and weakly. I think its probably just his time, but I'm also wondering if he's starving, I can never tell if he eats much

 

[mrsjoannh13]

Maybe drop some sinking food in at night before you go to bed. Less chance the guppies will get the food as I don't think they are nocturnal feeders like corys.

Personally I'd try to move him into another tank (depending on what's in the other tank). Does he have any places to hide in the tank he's in? Plants, logs, etc.

He may also be a bit stressed as they like to be in groups of 5 or 6 of their kind.

Can you also post your water parameters? Ammonia, nitrite, nitrate, pH, GH, KH, water temp? And what substrate do you have?