While we have no hesitation in rushing out dogs and cats to the vet on a regular basis, we sometimes forget that fish too, need love and care in order to lead a healthy, happy aquarium life. Fish in fact, are prone to several afflictions, so it’s worth knowing a little about the most common, to ensure you can keep an eye on your fishy friends, and keep them in top notch condition.

Here are just a few of the more common problems that can occur:

Head and Lateral Line Disease (previously known as Hole-in-the-Head disease)

No, it doesn’t sound good, does it. Head and Lateral Line Disease comes about from a deficiency in either Vitamin C, Vitamin D, calcium or phosphorous. This may result from a lack of variety in the diet, a poor diet lacking in nutrition, not enough water changes, or sometimes even over filtration with carbon. Symptoms to watch out for include small indents or pits in the head and face, which usually start just above the eyes. If left untreated, these can grow into large cavities which then spread the affliction through the body.

It’s worth noting there is another disease called Hexamita that seems to attack fish at the same time as an outbreak of Head and Lateral Line Disease. Hexamita is an affliction that affects the lower intestine.

Treatments for Head and Lateral Line Disease include adding vitamins to the diet, most often via frozen food or flake foods, extra greens (yes, they’re not just good for humans), a decreased incidence of beef heart in the diet, an increased frequency of water changes, and the removal of activated carbon filtration.

Swim-bladder Disease

Swim bladder problems result in the fish having difficulty maintaining balance and equilibrium, and as such they develop an abnormal swimming pattern. When this happens it is frequently a sign of another problem such as a congenitally deformed bladder, cancer or tuberculosis in organs in close vicinity to the bladder, a parasitic or bacterial infestation.

It’s recommended to treat this problem if you believe that is what is troubling your fish. If you have ruled out any of these other possible ailments, the next step is to ensure the fish is not constipated. Try feeding it only live food for a period, or squashed frozen peas can be beneficial (adding roughage to the diet). It’s also worth checking the aquarium temperature to ensure it is stable.

Constipation, surprisingly, can affect some fish regularly, most often because of a poor or unsuitable diet. The symptoms to watch out for are a loss of appetite and a swelling about the body. In most cases, simply switching to a healthier, more balanced diet and adding extra roughage short-term, will help the fish to get rid of the constipation. Where this doesn’t have the desired effect, some people opt for dried food that has been soaked in medicinal paraffin oil, glycerol or castor oil. So yes, a well-balanced diet is a must, even for your pet fish!

Eye Problems

There are several eye problems that can occur in fish, so their eyes should be monitored for anything out of the ordinary. This might include swelling, cloudy eyes, bulging eyes, or an eye that appears to be opaque. Swollen or bulging eyes (pop eye) can result from a fish being handled roughly, a gas embolism, tumours, infection or a Vitamin A deficiency. Again, antibiotics or penicillin may be of benefit depending on the cause. Eyes that appear to have turned opaque are often the result of poor nutrition or sometimes a metacercaria invasion (these are grubs). A change in diet and the addition of extra vitamins are recommended.

Blindness is unfortunately the end result for some poor fish who have suffered from poor nutrition or even from too much light. To prevent this, it’s advisable to always feed your fish a varied, vitamin rich, nutritious diet, and to ensure their environment is lit suitably.


It’s interesting to note that while tumours may result from cancer or a virus, most in fact are actually genetic, being the result of too much hybridization in the course of breeding. Sadly, it’s rare that a tumour can be treated, so if the fish is suffering, the best course of action may be for it to be humanely destroyed.


Yes, accidents happen, even under the most astute supervision. Sometimes this is the case of unsuitable fish being put in the same aquarium, with aggressive ones prone to eat or nip at smaller fish. Or it might simply be a case of a fish tangling itself on the aquarium d