I am unsure whether there is something wrong with my severums or whether it is just what they "do". I have 4 small golden severums in a 4ft 65g tank. They all eat voraciously (bloodworms, cichlid pellets, crushed algae tabs and a constant supply of aquarium plants) and seem to be happy, aside from a few things...

They seem to all have a habit of head standing, or floating with their heads facing the bottom of the tank for short periods of time before resuming usual swimming. The smallest ones seem to do this when the large one approaches almost as a submissive behavior, reminding me of a dog rolling onto it's back.

Also, all four seem to have grey discoloration some places on their bodies. I can't quite tell if it is where scales have been scraped off. I originally thought they were just colored that way but sometimes the grey goes away and come back. I have tried taking photos but it doesn't seem to show up.

The third unusual symptom is that 2 or the severums have a very obvious red vein or line running along the base of their anal fin and caudal fin. They have had this ever since I got them. Should I be worried about it?

Thanks in advance.