“…GH production and growth regulation are primarily controlled by a complex regulatory system and, to some extent, both are coordinately regulated by common factors (Bjornsson et al, ; Chang & Wong, ; Reindl & Sheridan, ). Historical data demonstrate the direct effects of GH on growth and development of different fishes (Cao, Zhou, Wei, Li, & Gui, ; Khalil & Mousa, ). Our results concur with previous findings which reveal that serum GH levels are positively correlated with growth performance in African catfish, Clarias gariepinus (Wang et al, ), Atlantic salmon, S. salar (Bjornsson, Stefansson, & Hansen, ; Stefansson et al, ), coho salmon, Oncorhynchus kisutch (Young, Bjornsson, Prunet, Lin, & Bern, ), gilthead sea bream, S. aurata (Perez‐Sanchez, Marti‐Palanca, & Bail, ) and Nile tilapia, Oreochromis niloticus (Qiang et al, ).…”