Microscope

An essential aid for the serious Koi keeper, that empowers the user to positively identify the pathogens causing an external disease. Effective microscopes are available from just over £100 right through to over £1,000. Fresh samples of mucus for viewing under a microscope can be collected from suspect koi using a glass microscope slide, pulling it gently along the dorsal flank of a koi in a backwards direction. The mucus can then be 'squashed' under a wet cover slip, and viewed under low power magnification.

The typical 'light microscope' will have a light source beneath the slide shining up and through the two lenses of the microscope. The two lenses are the eye piece (typically x10 magnification) and the objective lens, (closest to the slide and ranging from x2.5 to x100). Therefore the compound magnification of the microscope will range from 25-1000x.

The mucus sample should be viewed at the lowest magnification first to make focussing easy, and then viewed if necessary under progressively more powerful objective lens. Amongst the random textured mass of a mucus sample, offending parasites can easily be viewed as those well-formed, regularly shaped and moving objects. These can then be easily identified using an appropriate guide on disease organisms.

There are many proprietary treatments readily available, but the difficulty remains in positively identifying the problem - there is little point in treating something that isn’t there, that can also build up resistance to the treatment. Quite often the problem relates to water quality not parasites, and a microscope can rule out the latter very quickly. Of course we appreciate that those whose expertise and skills lie in keeping fish are unlikely to have extensive experience in microscopy.