I have two pearl pups I bought a year ago one is growing big the other seems as it hasn't growled at all starting to get worried any help would be greatly appreciated
You have two very beautiful pups
It has happened to me on more than one occasion where one pup grows much quicker than the other, every time this happens and I check, its always the female that grows quicker than the male. Not sure if it happens to other people too
What are you feeding them and how often?
Are there other fish in the tank?
I really like your tank layout. Normally, I don't care for white substrate, but in that tank, it actually looks like the best choice to me.
As to growth, I haven't kept rays, but generally speaking, sex will definitely impact growth, Also, even perfectly healthy fish that are the same sex don't grow to the same size or at the same rate. Genetics plays a part on both aspects. I'm guessing that would be true to at least some extent in rays as well.
Also, what are your nitrate levels? Nitrate levels can inhibit hunger and if they are high enough, it could be that one is affected more than the other.