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.
Analysing pathogens
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.
Necessary treatments — bacteria
Back to our first aid box. Alongside a quality liquid test kit, there are a few key items that would be suggested to take up permanent residence. The first of which is a high-quality antibacterial product. You’ll encounter a whole apothecary of options on the shelves of whichever vendor you look at, so a basic understanding of active ingredients is helpful.
With bacterial infections you will commonly see products based on malachite green, formaldehyde/formalin, and acriflavine. For the most part these will handle many of the bacterial issues you may come across quite effectively. These are well worth having on hand for a quick-response product.
Handling fungi
The next pathogen group that can pop up and cause us heartache is fungi, an expansive family of organisms that most keepers will be acquainted with in the form of Saprolegnia and its relatives. Most often this will manifest as white, fluffy fungus developing over uneaten food, or fish eggs, but additionally it can also penetrate and set into wounds, where it can flourish on any dying flesh (and subsequently kill more off, to give itself an ongoing food source).
Fungal infections are almost always taking advantage of something else that is wrong — they rarely establish on their own, and most commonly occur around a physical injury, or on the tissue damaged by bacterial infections (such as ulcers). In these instances, you will find medications based on methylene blue as well as the malachite, formalin and acriflavine found in antibacterial treatments.
As an interesting note, methylene blue is a useful product in its own right when used as a bath or painted directly on to the affected area. In these cases, the methylene can stain the fungus, but other tissue types (such as necrotic tissue, or sloughing slime coat) will also turn a deep hue.
The small parasites
Next on the list come treatments for protozoa, with the most familiar example being Ichthyophthirius multifiliis — commonly known as whitespot or increasingly (especially in the USA) as ‘ich’. One important point with Ichthyophthirius is that not all white spots are whitespot! In this instance, I would refer you to the work done by Dr Peter Burgess, a long-time PFK contributor and authority on the subject. His work shows that I. multifiliis pathogens need to be introduced (usually with an infected fish being the disease vector), and don’t exist in a state of dormancy, waiting for years in the shadowy corners of your tank to leap out and cause trouble. If you haven’t recently added new fish to your set-up recently, but suspect a whitespot outbreak, then you are likely barking up the wrong tree.
Other diseases, bubbles, and even grains of sand caught in a fish’s mucus, have all been misdiagnosed as whitespot before. Protozoa are susceptible to a variety of medications. Once again you will see malachite green make an appearance on protozoa medication ingredients, as well as copper sulphate, ethacridine lactate, formaldehyde, and a few others. Treatment is usually quite effective once undertaken, and as long as they are used correctly there are few repercussions to filtration, plants or long-term fish health.
The big parasites
A sometimes-overlooked place in my medicine cabinet is dedicated to the larger parasites, and specifically worms. Here again we need to consider the fish in question before medicating. Whilst in some cases we will be able to visually identify the issue (Camallanus are easy to diagnose as you will spot them hanging from the anal vent of the infected fish), in others there is often an urge to diagnose a worm infestation as a kneejerk reaction to a set of symptoms, rather than making an informed judgement. Before reaching for the medicines, consider the origin of the fish. Pretty much any wild caught species has an increased risk of carrying parasites, and whilst most good stores will medicate fi sh upon arrival, this may not always be the case, and as such should be done by the hobbyist upon receipt. Ideally, this will happen in a quarantine setup.
Second consideration should go to the diet of the fish. A captive bred and raised fish that has only ever been fed prepared foods such as flake is extremely unlikely to be carrying an infection of this nature (barring the possibility of another fish in the tank coming in with a different background, of course). In order to bring the parasite into the tank, much like with whitespot, we need a vector; often in the form of live food. In these instances, periodic treatment with a reliable medication is sensible.
In terms of active worming ingredients, I favour levamisole (as is found in eSHa NDX), though more commonly you will see flubendazole (as found in NT Labs Anti-Fluke & Wormer). The two medications have slightly different methods of action, the former being effective as by interfering with muscle control in adult worms (stopping copulation), and the latter interfering with a protein called tubulin to inhibit cell function and reproduction.
Whichever specific products you purchase are of course dependent on what is available to you, your own personal brand preferences, and likely the opinions and feedback from fellow hobbyists, nevertheless, whichever your choice, it’s better to have them to hand and not need them, rather than face a microbiological battle without any weapons in your arsenal.