Someone spent a good deal of time on that tank. At first glance I thought it was an ACE Supertank, but if it is it is still highly modified.
I'm not sure but I think it was a custom one off tank? If I recall correctly it was around 10 gallons. Maybe someone knows who's it was and can chime in.
Here's a closer picture of the tank, you can see where they had to form the tank around the imitation velocity stacks.
