Hi Ursula,
Online groups can be helpful, but often there are people with good intentions who give advice that might not necessarily apply to your bird’s situation. Your first action should be to take Cookie to a board certified Avian vet for a thorough exam, including bloodwork. While this can be expensive, it is better than trying to guess what is going on. I am actually concerned that you are over-supplementing his diet. Nutri-Berries have 100% of the nutrition he needs – they are nutritionally balanced the same as a pellet, but they are not ground up. However, in order to get the full benefit of the food, Cookie needs to eat most of each berry and not be allowed to just pick out his favorite bits and discard the rest. If he does this, you need to reduce the number you give him and not give him more until he has eaten all of each berry he has. He will learn to eat them completely if you limit what he gets at a serving. If he is eating the Nutri-Berries completely, he does not need additional vitamins – especially something like Nekton that tends to be very concentrated.
The other foods you are offering are fine as long as they are in small amounts. I would encourage you to try to get Cookie to eat more veggies and maybe some dark, leafy greens. Amazons tend to have an issue with fat and this can also involve their liver. They are often not as active as other species and they do love their food. My Amazon had weight and feather issues until I put her on a diet of Nutri-Berries, fruits and veggies. It took a year, but she lost the weight and her feathers were bright and healthy after a couple of molts. So keep in mind this may not be a quick fix, and you won’t see changes until after each molt, but I am fairly certain this is a nutrition issue.
Thank you for asking Lafeber,
Brenda