A koi carp with severe fluke infestation has lost body weight and hasreddening to the head, shoulder, ventral fin and tail base.

Gill flukes are a common parasite found in both fresh and saltwater aquariumfish. They prefer to attach to the gills but can also be found feeding onmucus and skin cells anywhere on the body. They use hooks to attach to fishand cause significant damage to the gills and skin through attachment sitesand their grazing activity. This damage can then allow bacteria to invade,resulting in a high death rate.

The flukes are so small that they are invisible to the naked eye, and requirevisualisation with the use of a microscope. They are flat worms that resembletiny leech-like creatures. Pictured is a single gill filament hosting two gillflukes (star). The paleness of the gill filament indicates the fish isanaemic. The flukes cause so much irritation that the mucus layer (arrows) hasgreatly expanded.

Fish that are infected may hide, become lethargic, have clamped fins, adecreased appetite, “rub” their bodies on surfaces, and have difficultybreathing or lose scales. Environmental conditions such as over-stocking,aggression, poor water quality and incorrect nutrition can lower the immunesystem’s ability to combat the infection.

Gill flukes have a direct life cycle, meaning they are contagious and spreadfrom one fish to another. In recirculating systems, with fish stocked at highdensities, the number of parasites can increase exponentially. It is a ticking“time bomb”.

The best way to avoid disease caused by gill flukes is by implementing aquarantine protocol. If gill flukes have been diagnosed, treatments caninclude: freshwater dips for marine fish or saltwater dips for freshwaterfish, praziquantel, formalin, trichlorfon or copper. Gill flukes lay eggs,which can be particularly resistant to treatment, so repeated treatments arerequired. Consult a fish veterinarian to help check whether you have flukes,and they can formulate the best method to control and eradicate flukes fromyour system before you have a disease outbreak.

Biography of Dr Karlee Hirakis

Dr Karlee Hirakis is a member of The Fish Vet’s team, located in Sydney andoffers mobile veterinary services for aquatic patients. After graduating fromThe University of Sydney in 2013 she has worked in rural mixed and smallanimal practice on the central coast of NSW and in Sydney.

Dr Hirakis has kept numerous different types of fish throughout her life andenjoys the challenges that come with practising veterinary medicine in aunique environment. At home, she is kept busy looking after her two Dobermandogs, a cat and seven fish tanks.

Dr Hirakis is currently awaiting approval to become a certified aquaticveterinarian through the World Aquatic Veterinary Medical Association. Thisprogram includes over 150 hours of theory and practical work in aquatic animalmedicine.

The Fish Vet – Sydney

Email: [email protected]

Previous Why our dogs don’t look like wolves: Research uncovers genetic cluein domestic animals

Next Dog Lovers Show – Sydney and Melbourne