I have a Fish. Bought it back in '94 I believe.
I used to run it through the 2150. Now I have the Classic 2100.
I used to have those T-75s in a 4-12. Now, I have Greenbacks. Big difference. Way better. Probably the single best thing I ever did for my sound.
That presence control is strange. When you turn it all the way up, the volume drops, and it compresses immensely. But, it doesn't seem to add any high end, maybe a little bit of fissile in the upper mids. If you're looking for a heavier, metal type tone, run the presence all the way clockwise. Compresses. For a bigger, open, less compressed sound, turn it all the way counter clockwise.
I never had an issue with too much treble in the sound. And, I'm not a big treble sound kind of guy. I run the treble at about 9-10 o'clock on the brown channel.
Mine has the mod for the Shark channel, instead of a switch for the dark/bright, it has a knob. More control with it. I don't use the Shark channel too much.
Also, on my power amp, I run the presence and depth knobs all the way off.