nice photo's bradley,
I love the Gonipora and acan?(third last pic) i love the crop you've done on it
most of your pics are a bit soft, which is most likely camera shake and/or movement from fish. try shooting at a higher ISO (800 or 1600). this will add noise but everything will be sharper.
Always also remeber to focus on the eye of the fish. this is what people look first when looking at wildlife. try setting the focus point to your centre for better focus control.
the last picture of the full tank the whites are blown out but yet really dark.
i'd love to see the gonipora in a tight crop like the acan
Depp