Goldfish Care Guide

Cared for goldfish rarely get sick, even when old. In the early days of an aquarium, however, when you’re still buying new fish for the tank, it’s very easy to introduce goldfish diseases or parasites.

Let’s consider the most common goldfish diseases:

• White spot (aka ick, aka ich): Easily recognised by small white spots that appear over the goldfish’s body and fins. Highly contagious. If caught early when there are few spots, ick can be cured with off-the-shelf treatments you can buy from your usual retailer. You’ll need to treat the whole tank. The later stage, when the white spots are very numerous and the fish is breathing rapidly, is typically deadly, as the tiny parasites overwhelm the poor victim. Don’t delay!

• Fungus: Fluffy cotton wool-like growths that appear on the fish’s body or tail, fish fungus responds well to proprietary treatments. Brief saltwater dips using special brine salts can also be effective, provided they don’t overly stress the fish. Since fungus typically only affects one fish at a time, it is best to move the patient to a separate hospital tank or large bowl, which should be kept clean via frequent changes of aged water. Note: A special kind of mouth fungus is much more difficult to treat, and may only respond to antibiotics from a vet.

• Fin-rot: Ragged fins or a white-edged tail are the main symptoms of fin- or tail-rot. This disease is caused by bacteria, and usually only occurs in goldfish when a tank is over-crowded, under-filtered, or poorly maintained. Spring-cleaning the tank by performing several large water changes and boosting the filtration or aeration often leads to a recovery, but you must deal with the underlying cause. Proprietary anti-bacterial treatments are available; these are most effective in a separate hospital tank.

• Dropsy: A bloated body and scales standing away from the fish are a sure sign of dropsy. This is one of the worst diseases your fish can possibly suffer from; no treatments are reliable. Afflicted fish must be removed from the aquarium immediately, before they infect their healthy brethren. You can try to cure the fish using (expensive) antibiotics if available from your vet. Keep the fish in a small standalone aquarium, kept clean by frequent (at least twice daily) water changes. You might alternatively try some tonic/brine, as per the manufacturer’s instructions. Sadly, in most cases the kindest thing to do is to put the unfortunate fish to sleep as humanely as possible rather than prolonging its suffering.

• Skin flukes: These tiny creatures irritate the scales of the fish, causing it to flick and scratch against the rocks. Appropriate remedies from an aquarium store provide an effective cure; you may need to treat the whole tank, but it’s better to move affected fish to a hospital aquarium. Beware: white spot can cause similar symptoms yet the treatments required are different, so carefully observe your fish to ensure you make the correct diagnosis. It is usually a bad idea to mix two or more fish medicines.

• Leeches: These are just what they sound like: wriggly leeches that attach to the body of the fish. They’re rare in aquariums, although they’re sometimes introduced with live food, but they can attach to goldfish kept in ponds. Catch the afflicted fish and give it a 20-minute dip in a light aquarium brine (or ‘tonic’) solution, made up according to the manufacturer’s instructions. The leech will typically drop off. If not, it will be more easily removed with tweezers. Look out for re-infestation

• Gill flukes: If the fish hangs motionless in the water, particularly at the surface, with enraged red gills, suspect a case of gill flukes. This deadly disease can be treated if you spot it in time; consult your aquarium store as to the appropriate anti-fluke water treatment. The parasites are very contagious so you may need to treat the whole aquarium. Read the instructions carefully.

While many goldfish diseases can be beaten if caught early, prevention is far better than cure. A deterioration in water quality caused by a broken filter or careless over-feeding can easily stress your fishes, reducing their ability to fight off pests and infection, so keep your tank in tip-top condition.

In an ideal world you’d quarantine new purchases to save your fish and yourself a lot of headaches, but we realise in the real world not everyone does this. Please do consider setting up a small aquarium for quarantining new purchases. Once your tank is fully-stocked the quarantine unit can go into storage until called upon for hospital duties.

If you’ve got any high-quality pictures of your own goldfish suffering from the above conditions, please consider letting us have one for the site. We’d love to update this page with pictures of symptoms of goldfish diseases to help other goldfish keepers, but our own fish are (happily) in exceedingly fine fettle.

Filed in: Diseases