I checked out Turquoise Severums on Google and it seems maybe it could be a "Blue" Turquoise Severum but dont know if that's even a real type.

He looks like my turquoise. I dont have a good current photo but here he is when he was smaller. View attachment 1334858
Hes a bit larger now and his ventral fins have taken on that color like the one in your photo.
Ahh I see , Good looking Severum btw , is yours just as dark as mine currently?
Yes hes normally that color. In my pic he is flashing stress bars. I'll try to snap a pic of him later on. Again, im not 100% on it but pretty sure.
Thank you appreciate it , on a side note is your aggressive? Mine seems to be very aggressive where as my Red spotted Sev is extremely docile
Is he aggressive to everybody or just the other severum? He appears to be a male (again not 100%) so if hes attacking the redspot you could have two males.
Mine is not aggro. He gets bullied by my larger gold sev when shes not breeding with him lol.