Aquarium care involves a lot of aspects, including tank cleaning, water changes, and more, but what it all comes down to is one thing: the health of your aquarium’s ecosystem. Every maintenance task you do is performed with the end goal of ensuring that the fish in your aquarium stay healthy and active.
But, like any other organism, fish are susceptible to hundreds of different potential illnesses. So how do you know if your fish is sick? And what can you do to prevent it?
The first step is to monitor your fish daily and learn to identify different varieties of disease. The second is to implement an aquarium care regimen that will help prevent disease from taking hold in the first place. Here’s some advice for each of those categories to help you keep your fish strong.
Also be sure to check out our more complete overview of the different parts of aquarium maintenance!
Disease Types and Symptoms
You should begin by inspecting your fish every day to watch for symptoms of illness. The 
illnesses you should be looking out for can be separated into a few basic categories, and learning them can help you identify what it is you may be seeing.
Viral infections are some of the hardest types of illness to diagnose and to treat in fish. They’re often caused by bad water conditions and then spread through water or via contact between fish. One of the most common kinds of viral infection in freshwater fish is cauliflower disease, or lymphocystis, which creates white cauliflower-like growths on the fish’s body.
Bacterial infections often spread from fish to fish within a tank, and so should be immediately addressed with quarantines and antibiotics to prevent the threat overtaking the aquarium’s population. Common bacterial infections include dropsy, mouth fungus, fin rot, and hole-in-the-head disease, with symptoms ranging from swelling, discoloration, frayed fins, cloudy eyes, sluggish behavior, and lack of appetite.
Parasitic infections are similarly prone to spreading through your aquarium before you even know they’re there. Common examples include ich (white spot disease), nematodes, anchor worms, and gill flukes, with symptoms such as body growths, redness and discoloration, clamped fins, and odd behaviors like rubbing up against objects. Typical treatments for freshwater fish include medications, saltwater baths, and temperature increases.
Fungal infections tend to come after some other injury or illness which has weakened the fish’s ability to fight off infection. Common forms include gill rot, body fungus, cotton mouth disease, and systemic fungal infections, with symptoms taking the form of greyish or white fuzzy-looking growths appearing on the fish’s body, gills, and mouth, eventually killing it. If discovered, these should be treated with 10mL of 1% phenoxethol solution per liter of water in the aquarium.
Aside from infectious diseases such as these, there are of course other miscellaneous ailments. Sometimes, physical injuries just happen as a result of accidents, sharp pieces of décor, or bullying from other fish. In these cases, a bit of 2% mercurochrome should help treat the injury, as well as being kept in very slightly acidic water if the fish has a good tolerance for it.
Other maladies include constipation, which most commonly affects fish with compressed bodies like angelfish and can be cleared up with dietary changes and food treated with paraffin oil. You may also encounter tumors, which are almost always untreatable and require the fish to be put down.
If you aren’t sure what type of illness your fish has, try using this diagnostics tool—it allows you to mark all the symptoms you’ve observed, and then provides you a list of possible causes in order of probability.
Aquarium Care for Disease Prevention
So, what can be done to prevent those illnesses from making an appearance? Well, there are plenty of aquarium care tasks you can perform to protect against disease.
The first step in aquarium care is to make sure you’ve allowed your tank to cycle before you start adding fish. You need to give the aquarium time for the nitrogen cycle to build up sufficient amounts of the good bacteria responsible for converting toxic substances like ammonia into nitrite and then nitrates, an essential part of maintaining the health of your fish. Adding fish to a tank that hasn’t been properly cycled yet, or adding too many fish too fast, can lead to ammonia poisoning, algae blooms, and stress that makes them more susceptible to disease.
You should also quarantine your fish for at least two weeks and observe them a bit before 
introducing them to the aquarium. This way you can monitor them for any potential infections that they may bring into the tank and spread to the other inhabitants, as well as allow for a smoother, more stress-free transition for them.
Once the fish are in the aquarium, proper aquarium care should be practiced to maintain fish health. A nutritious and varied diet will help keep the fish healthy and vigorous just the same as it does for any other creature, ourselves included. Keeping up with weekly water changes and closely monitoring temperature, pH, and ammonia and nitrite levels are all key to good aquarium care.
However, one should keep in mind that it is possible to go overboard with aquarium care to a point that actually harms fish health. This may sound odd, but overcare is something many owners are guilty of. Using lots of pH-altering additive products due to an obsession with the “perfect” pH, as well as changing too much water at one time, creates an environment of shifting, unstable conditions that put a lot of constant stress on fishes’ bodily systems. If this sounds like something you may be doing, then you may want to take a step back and review the recommendations for these aspects of aquarium care so you’re sure you’re not inadvertently hurting your fish.
Of course, since there are, as mentioned, literally hundreds of different diseases which can afflict a fish, even the most experienced aquarist can’t prevent them all. Sometimes you just have to be vigilant so you can catch it early if something does occur.
Regardless, if you have further questions about prevention, diagnosis, and treatment, or any other aspect of aquarium care in Crystal Lake, contact Living Art Aquatics. We have the sort of specialized expertise you won’t get from employees at a big-box pet store, so simply give us a call at (847) 737-5151 and we’ll help you take your aquarium’s inhabitants from green around the gills to happy as a clam.