I recently got lemon tetras from Petco. I bought 8, 6 from one tank 2 form another. The 2 from the 2nd tank were the normal yellow fish with red eyes. The 6 from the other tank were smaller, probably younger, but had silver color and normal eyes. I've seen them both ways from watching videos and am not sure what is up. Are the not colored up ones juveniles or possibly females? The first image is going to be a not so helpful picture of what I'm referring to, I'll post 2 others from the internet to show what I am talking about with the differences. Thank you for any help!