Common Fish Diseases & How to Treat Them

Keep Your Fish Healthy

Once you add fish to your aquarium, you should always be mindful of their needs. There are many common fish diseases that can affect your finned companions that are easy to avoid and a little difficult to treat. Learn more about the four most common fish illnesses, how you can prevent them, and what to do if your fish has them. Read on for expert tips from Modern Aquarium!

1. Cotton Mouth

Cottonmouth (also known as Columnaris) is a bacterial infection that affects some tropical and cold-water fish. At first, you might think your fish has a fungal infection because of the grey or white spots on your fish’s head or body. Eventually, the spots spread and turn a yellow/brown color.

Treating this fish disease involves changing up to 50% of the water in your tank and siphoning the aquarium gravel (if you have any). Some medication requires the removal of the carbon from the tank’s filter throughout the treatment. A number of fish medications can help to treat cottonmouth. For example, KanaPlex Bacterial & Fungal Fish Treatment or Bactocide 1. These medication is added directly into your aquarium.

2. Dropsy

Your fish might have dropsy if their stomach is distended and they lose their appetite. It’s one of the deadliest fish diseases and may be caused by various factors. It is generally believed that it is caused by an infection brought about by negative gram bacteria which attacks a fish's weakened immune system. Consequently, by providing your fish with high-quality food, good living conditions, such as clean water and appropriately stocked tanks, you will avoid its occurrence.

Once a fish has dropsy, you should separate it and treat it with antibacterial medications such as Broad Spectrum Bacterial, Fungal & Parasitic Disease Treatment. It is also crucial to feed your fish the best quality food you can find and maintain high water quality.

3. Fin or Tail Rot

A fish with frayed fin or tail edges that have a white tinge is suffering from rot. A fish with this disease may also settle at the bottom of your tank and stop moving. This fish illness can be caused by poor water quality or bullying by other fish.

The best way to prevent this fish disease is to test the quality of your water regularly. Once your fish already has the rot, you have several options. Treat them with bacterial medicine (like Erythromycin, or Bactocide 2), complete a 25% water change, or isolate the fish if it’s being bullied.

4. Fungal Infections

Among the most common fish diseases are fungal infections which can result in white wool-like growths along the fish’s body, around their mouth, or on their gills. Fungal spores occur naturally in any aquarium, but stressed or sick fish can dangerously increase fungal levels.

Avoid fungal infections by isolating sick or stressed fish in their own tanks and treat them with the right fungal medications. It is also advisable to make a large water change of 30-50% and to treat your fish with an antifungal medication.

Most fish diseases tend to occur due to poor water quality which brings about stress and weakens fish’s immune system. To keep your fish healthy and happy, make sure you have adequate filtration, and test your water often!