The earliest stages of a disease are critical, and need to be diagnosed and treated promptly. Tom Ackrill looks at a few of the basics you should be keeping to hand.
Diagnostics in fishkeeping aren’t like CSI or human medicine. We have a limited number of medications available for our pets, and even more limited resources with which to make our diagnosis and then choose a treatment.
What does help, however, is having at least a basic first aid kit to hand so that if the worst does happen, (and inevitably, when it does happen it’ll be late at night, or on a Sunday when nothing is open) you can at least start the process of treating.
Start with a test
You might only have one sick fish, but we have to look at things holistically — taking the whole picture of our tank into account. This means we have to start at the top level, namely the environment. And in this case that means the conditions within the tank.
Your first essential is a decent liquid test kit. Whilst dip-test strips can give an indication of what’s happening with water chemistry, they degrade over time with exposure to atmospheric moisture, and are considered less reliable.
Knowing what the key water parameters are (which at the very least consist of ammonia, nitrite, nitrate, and pH — though GH and KH can also be extremely useful) can tell us a myriad of things going on within our environment.
For example, damage to fins, blood streaking in the fins, inflamed gill tissue, problems swimming, sudden deaths — all of these can usually be linked back to deteriorating water quality and chemistry.
In these instances, there may be no pathogenic element involved.
The issue here will be an environmental disease. You should, of course, also conduct an investigation into what that is and resolve it. Is the filter working as it should? Is there a dead body contaminating the tank? Have you not carried out a water change in months (or longer)?
Alongside parameters, consider your husbandry. Some pathogens thrive in tanks that are overstocked and neglected. Organisms which are usually harmless (your tank is full of these — it’s a cornucopia of opportunistic protozoans, fungi and bacteria) may only have the potential to become pathogenic and attack livestock when conditions in the tank have deteriorated. As with most situations, prevention very much is better than cure.
Once we have taken these environmentally-derived possibilities off the list, we can then start considering other options.
Broadly speaking, we won’t be able to hone down to a single definitive answer on what is causing our issue; in many cases we refine as far as ‘bacterial,’ ‘fungal,’ or ‘parasitic,’ and that is as deep a dive as we take.
To go beyond this level does require the sorts of tools that the average hobbyist will not possess, plus the nous to the interpret what those tools are presenting. The most common option seen is probably what is termed as a ‘scrape’, where a sample is taken (gently scraped) from the outer mucous layer of a fish, fixed onto a slide, and then observed under a microscope.
With detailed knowledge of this microscopic world, the data gleaned here can be invaluable. However, there is a need to know more beyond recognising shapes. Often organisms will be seen on a slide which have the potential to cause illness, but are in fact part of the standard fauna of the fish, and only become problematic when conditions allow. A great example is Trichodina which in normal conditions is present in the mucous layer of a fish in the same way humans will carry organisms such as Candida or Staphylococcus. At low levels, they are simply passengers along for the ride.
The risk is that an overzealous eye can offer up an incorrect diagnosis if it’s based solely on noticing the presence or absence of an organism, as opposed to assessing the exact type and quantity of said organism. If you go down the microscope route, take care to understand the mechanics of what is being observed — and essentially, what is considered normal — rather than simply knee-jerking over what is there.
Don’t miss an issue and subscribe! Practical Fishkeeping is Britain's best-selling fishkeeping publication, filled with species showcases, fishkeeping answers, advice, competitions, amazing features and much more!
We have a brilliant trial offer on both print and digital of JUST 99p for your first issue!