Recently I have started photographing fish and crustacean larvae using my Nikon D7000, 105mm macro lens, a set of extension tubes, flash unit and tripod. I also use 2 desk lamps with daylight bulbs and pieces of polystyrene to achieve reasonably good lighting. Here is an example of what I’ve been able to achieve so far using this set-up:

I’m quite happy with the results of this set-up. However, having recently had the opportunity to study these animals under a microscope (borrowed from a local university), I could immediately see the benefits of using a microscope for this kind of photography work.
The microscope I used was a basic stereomicroscope with around x5 zoom magnification. The microscope obviously provided greater magnification than my macro lens and extension tubes, but the other main advantage was the ease of focusing through the eyepiece tubes (the image through my camera’s viewfinder is often very dim). Also, the microscope was far more comfortable to use than my current camera set-up, since I have to stand over my camera looking down vertically through the viewfinder.
So I am looking for advice as to what kind of microscope and camera attachment would be suitable for achieving photos similar to the one above, but with improved sharpness and magnification. The aquarium is looking to buy a new microscope for general observational purposes and I would like to be able to use it to photograph these animals so that the pictures can be used in the aquarium’s educational materials/displays.
I don’t think that I’ll need magnification greater than around x5 (I expect that I will do most of my photography between x2 to x5). I would also like enough room between the lens and subject to be able to easily change the position of the petri dish (or a similar container in which the animals are held). I would also like to continue using my dslr with the microscope, although I would consider changing it for a mirror-less compact if this made it easier for attaching to the microscope.
I’m not very familiar with microscope companies, so I’ve only looked at some of the leading brand names which I’m aware of like Olympus and Nikon. I was considering something like a Nikon SMZ800 with a P-Plan APO 0.5x or 1x objective, P-IBSS2 beam splitter, and a C-BD Bright/Darkfield Stand (to achieve similar lighting to the photo posted above). From reading other posts on this forum, I understand that stereomicroscopes are not the best choice for photography. However, since I won’t be going much above x5 magnification, will image quality not suffer too much? Or is there another microscope design/brand/set-up you would recommend?
Any thoughts or suggestions regarding this microscope or any other set-up which you think may be suitable for my needs would be much appreciated. Thank you.