That looks like an old case of frostbite. Where do you live? What was the weather like right before you brought him indoors to live?
To get frostbite on toes, he had to have been exposed to freezing temperatures and wet conditions, such as walking in puddles as the temperature was dropping with an incoming freeze event back in December.
Now there is nothing to do about it. His immune system is cleaning house and getting rid of his dead and damaged tissue. The black parts will be falling off soon. Then the swelling will subside and he will have short toes with no talons. That will make it hard for him to scratch around in the soil, but otherwise, he should do just fine.
To get frostbite on toes, he had to have been exposed to freezing temperatures and wet conditions, such as walking in puddles as the temperature was dropping with an incoming freeze event back in December.
Now there is nothing to do about it. His immune system is cleaning house and getting rid of his dead and damaged tissue. The black parts will be falling off soon. Then the swelling will subside and he will have short toes with no talons. That will make it hard for him to scratch around in the soil, but otherwise, he should do just fine.