Moved the tanks around. The T. dobrogicus seemed happier in a 40 breeder so I moved them back into one. The 75 gallon resulted in less activity and more hiding. I couldn't be happier. They are more responsive to eating and seem to all be in the mood to breed.
There is one male that is so much bigger than everyone else. He is older by a year. He is over 6 inches and as wide around as your finger. Hope they all get this big.