Latex probably won't stick to acrylic very well. Maybe it would if you used sandpaper to rough up the surface of the acrylic to get it to hold the paint... maybe not.
I'd use a spray paint designed specifically to stick to acrylic. Rust Oleum makes some as well as other brands I'm sure.
yeah, i was planning on sanding it
or even priming it first, then paint, then cover the paint with a clear epoxy.
my main concern if there is a health risk to the fishies
Krylon brand is an excellent multi-surface/multi-use spray paint. Previously, I could only get it commercially, but they have been selling it in Wal.mart stores to the general public for several years now. Good quality and dries in minutes.
I used the paint that they use to re-finish refrigerator parts and it works well. Moisture resistant, rust resistant. It's the bottle of spray paint with a refrigerator on it. It worked really well and stuck to my glass really easily.
Here, this stuff...