The line thing down the middle is actually a bend in
the tank. If you look at some of the other tank shots,
you can see the design and where the bend is.
This shows the three big guys, the Blue Diamond
(captive bred) on the left, the Green (wild-caught)
and the Heckel (wild-caught) in the middle and right
respectively. The Blue Diamond is about 5", the Green
almost 7" and the Heckel around 6".