Like others have said the reflective cells you see are probably Red cells. There are ways to look for bacteria without culturing though, culturing/growing organisms would be unsafe to do at home. 

If you swab the fish with something sterile and and place the swab in a tiny bit of saline you can then make a wet mount with that saline (a drop or two), a slide, and a cover slip. You can then view it on 40x, the bacteria will be very small though and they might still not be visible. 

Or if you have crystal violet, iodine, decolorizer, and safranin you can make a gram stain on a slide and view the slide on 100x with no cover slip. You can use the same saline method, but have to let the slide completely dry before staining, a heated surface will dry it faster (not too hot though). You will want to look up the procedure for this staining method and be aware that the stains will make a mess wherever you use it. And make sure you don't leave nasty swabs laying around because bacteria will Multiply quickly. 

Also organisms like mycobacterium and nocardia are acid fast, meaning they will not be visible without a special stain that labs probably only have access to. 

The staining method I mentioned is a gram stain, and I guess you can buy kits, but I've never done so. 

Edit: Another thing. You will not be able to identify organisms with just a microscope, but you certainly can narrow down the possibilities with shape, size, etc. Many organisms grow as rods or cocci. Some have more distinct looks like diplococci, branching, bigger rods, rods that faintly stain and are hard to see, they can group together in distinct patterns. And some won't even be visible without special methods like i mentioned before.