1. Loss of color – General body color begins to dull or fade. Darker fish loose their vibrancy and turn a more muted version of their usual shade or begin to turn a muddy brown or gray color. This could signify any number of things from poor water quality to an internal bacterial or parasitic infection. If the body becomes splotchy or one confined area becomes dull or gray you may have a bacterial or external fungal infection. Keep in mind that it is normal for a betta’s color to change slowly as it ages and older bettas will often get a “beard” or an area under the mouth that becomes dull or gray in color. Again, this happens slowly as bettas mature. Rapid color loss may signal illness or a visual sign that the water is inadequate. Test your aquarium’s water.
2. Clamped fins – What are clamped fins anyway? Clamped fins are when a betta holds his dorsal and anal fins close to his body and keeps his caudal fin closed tight rather than displayed open like a fan. Bettas don’t typically swim around in full display all the time but will often spread their fins wide from time to time, especially when another betta is in sight or when they can see their reflection. Bettas who rarely open their fins up wide may be telling you that they are unhappy with the state of their water or are feeling unwell. Again this is one small piece of the puzzle. There is no medicine for clamped fins. If you find your betta is keeping his fins clamped, start by checking that your water is warm enough and is free from toxins like ammonia, nitrite and high nitrates. Rapid changes in pH may also cause this reaction. If you notice clamped fins over a long period of time (say, several days) watch closely for other signs of illness and keep testing that water!
3. Lethargy or Sluggishness – For me this is the tell-tale sign of a problem. It won’t take but a few days for you to get to know your betta and his normal activity level once you bring him home. If you notice a sudden loss in energy, don’t ignore it. Bettas typically explore all day and sleep soundly (hardly moving) at night. A betta that lies on a plant or at the bottom of the tank all day is not a healthy betta. Sluggishness can signal virtually any illness but it also signifies that the water may not be optimal for good health. (Test that water – are you seeing a pattern in my answers here?) Lethargy may even be a sign that he isn’t eating a balanced and nutritious diet. If your boisterous betta suddenly becomes a couch potato, you’ll need to review all aspects of your care regimen.
4. Loss of appetite – This is another worrisome symptom of illness. In my experience, loss of appetite signifies that an illness has gone unchecked. Bettas, whose instincts are to survive, will continue to eat even when sick until they can no longer and must conserve vital resources (like digestion) in order to heal. This is why a betta that won’t eat really concern me; not to mention some of the most effective antibiotics are administered orally. A betta that won’t eat may not be getting the best medicine. The causes of appetite loss can be many, from bacterial to viral to parasitic infections. Usually poor water quality alone does not cause loss of appetite unless severe.
None of these symptoms of betta illness points to any one specific sickness but instead should be a signal to you, the betta parent, that something is wrong. If you observe any of these, take a few minute to assess what the problem might be. Look for other signs of disease, check all your water parameters and review your betta care regimen. The answer may be as simple as a water change, a couple of ticks on the aquarium heater, or a new brand of betta pellets.