Hi tetrafan
Unless your house is unusually cool, or you have one of the relatively few corys that require warmer than usual water, you won't need a heater for him.
You can probably put him right back into the big tank, but watch the wound for any sign of fungus. If you don't see any white fuzzy stuff forming on it, he will be fine.
Unless your house is unusually cool, or you have one of the relatively few corys that require warmer than usual water, you won't need a heater for him.
You can probably put him right back into the big tank, but watch the wound for any sign of fungus. If you don't see any white fuzzy stuff forming on it, he will be fine.