Black in the stool means he isn't eating much. New bird's sometime's won't eat much when changing homes for a couple days due to stress but I don't know if that's the case with your guy or if it just doesn't know how to eat or just not like what he's eating. We live in the same area, plenty of food is available in nsw, thats good atleast!
Some things to try:
-Ask the breeder exactly what he fed the parent's (it's likely the baby's were eating some of that on their own, this probably the best thing you can do, birds don't like change!)
-Try to reduce stress on him (put him in a safe quite corner and don't do things that fear him)
-Go out and buy different food (a seed mix with sunflower seeds included is what a lot of birds love, it's not good for them but at this point be happy if he eat's anything, also try some small pellets and soften them with some water, add some dry fruit n nut mix could work also, fresh vegetables like corn on the cob, carrots etc, alot of bird's like tropimix small parrot mix, try that if you find it)
He need's to start eating really soon or I would be very concerned, small amounts of fruit isn't enough! I would take him to an avian vet if he doesn't start eating soon, it's a good idea to do that with new birds regardless of signs or not. Goodluck!
