Featherfin Catfish (Growth Spurt)

[KirkyArcher]

I bought two of these about 4 months ago, both were the same size when purchased at around 2-2½" now one has grown to about 3" but the other one is very close to being 5" Is this difference in growth rate  indicating a possible issue or just the difference between male and female of the species.  I have heard that these fish are difficult to breed in captivity and that sometimes hormones are used to help, could this also be a cause of the rapid growth?
 

 

[N0body Of The Goat]

Could be the bigger one is the dominant of the two, getting first dibs at food offered at night, plus submissive fish can sometimes slow their growth rate right down (as if trying to "keep a low profile").