HWF refinish? Impact on fish tank?

[FishyFishy!]

I would seal the top of the tank the best you can (you could use some poly and a good tape), and leave a window open for air circulation. I think you'd be fine.

You could also make a tarp-like thing over the tank, seal it to the back wall and floor the best you can.

I think i'd be more worried about particles getting into the tank, than chemicals in the air.