Goldfish Illness: Treatment And Prevention Measures [Mega Guide]

Every single living thing can become noticeably subject to the ailment in specific conditions and fish make no exemption. Goldfish are hardy, but sometimes they become illness like all the inhabitants of the aquarium. Due to contamination of bacterial, protozoan, infectious diseases and so on, goldfish become unhealthy. Diseases occur in aquarium condition with wrong tank management. For proper treatment, diseases should be diagnosed accurately.

Categories of Goldfish Diseases

The goldfish illness can be partitioned into non-infectious and infectious diseases. Some infections are more susceptible to goldfish. Non-infectious diseases occur due to improper aquarium maintenance, exposure to external factors, improper feeding, as well as mechanical injuries while infectious diseases are caused by bacteria, fungi, viruses, unicellular algae, parasitic worms and arthropods.

How to Identify the Diseased Goldfish?

The health of goldfish is generally dictated by their versatility, brightness of color, sparkle of scales and appetite. There is another indicator on which you can instantly decide the condition of fish: if the dorsal fin holds the fish vertically, then all is well. When you see one of the signs of the disease, instantly and carefully watch the unhealthy fish. Thoroughly examine it, attempt to effectively distinguish the illness fish and then proceed to treatment.

General Causes of Goldfish Illness

  • ​Pollution;
  • Poor quality feeding;
  • Overstocking;
  • ​Large variations of water pH;
  • ​Introduction of new fish and decorations;
  • ​Inappropriate tank management;
  • Sudden changes of water parameters;

Signs of a Healthy Goldfish

  • Healthy fish should have brightness of color;
  • ​Healthy fish bears glossy clear eyes;
  • They move elegantly throughout the aquarium;
  • They eat food regularly and constantly;
  • They expand their gills regularly and timely;
  • They have clean and shiny scales;
  • They have always upright fresh fins;
  • Healthy fish eliminates their waste regularly;
  • Healthy fish do not have white spots or blotches on their body;
  • Healthy fish do not floating, move up and down and sinking;

General Symptoms of Diseased Goldfish

​There are many symptoms to diagnose the diseased goldfish.

  • Affected goldfish does not eat feed spontaneously;
  • ​They float upside down or float near surface and side of the wall of aquarium;
  • They move very slowly;
  • Red and white spots are seen on the body;
  • ​They generally gulp air at the water surface;
  • Fins become black in color;
  • ​Body becomes pale in color;
  • Gills become pale;
  • Protruding eyes are seen;
  • They rub against the aquarium glass and other objects;
  • ​Fluffy patches or discolored spots are seen on the body;
  • Mouth becomes reddish in color;
  • They don’t take food at all;
  • ​Bleeding wounds or sores are seen on the body;
  • ​Weight loss;
  • They breathe rapidly;
  • They take rest at the bottom;
  • They react slowly during disturbance;
  • Eyes become whitish in color;
  • Belly becomes red in color;
  • Red spots are seen on tail and fins;
  • ​Sometimes fins are folded or frayed;

How to Prevent or Minimize Goldfish Illness?

​To prevent or minimize goldfish diseases the following step should be taken:

  • ​If possible, buy fish only in specialized stores, where they try to sell healthy fish;
  • Bring new fish home; hold them for at least a week in quarantine;
  • ​Feeding live food to the fish: makes sure that it is caught from ecologically clean reservoirs, and always disinfects it using methylene blue;
  • ​Always observe the behavior of fish.In this case you should take help or ask for help from goldfish specialists, for example, a pet store;
  • ​Do not start treatment without consulting with goldfish specialists;
  • ​It is strongly advised for treatment to use special fish medicines;

Fungal Diseases of Goldfish

The fungus is a generally opportunistic pathogen and some are facultative.  Fungal diseases are sporadic problems. Saprolagiasis and Branchiomycosis are the most common and widely spread fungal diseases. Generally, the fungal attack occurs in early spring, late autumn, and winter. It affects weak fish that have weak immune system due to prolonged low water temperatures and poor tank environment. The fungus can infect any wound due to improper handling with hands, nets, containers or sharp decorations. Fish may get injured battling each other, or they may have open injuries from bacterial or parasite contamination. These injuries are at hazard for fungal colonization. The filthy tank environment also allows excessive amounts of the fungus to grow. Ammonia and other organic matter wear away the slime coats that protect the fish and cause chemical burns. These burns then also get infected by fungus.

General Symptoms of Fungal Diseases of Goldfish

  • sign-out​A white patch appears on the body of the fish;
  • sign-out​The fish is depressed, or “hanging” at the surface of the water;
  • sign-out​Swallowing the air,
  • sign-out​Lying on the ground;

Cotton Wool Disease or Saprolagniasis of Goldfish

Saprolagniasis is commonly known as mould or cotton wool disease. It is caused by fungal infection. It is one of the most common goldfish diseases. When a fish becomes injured during handling with hand, nets, containers or sharp decorations, it could be susceptible to cotton wool disease. This sickness is very simple to identify. It makes a cotton-like development over the fish’s mouth, fins, and body. The cotton lik development can be white, dim, or darker.

Causative Agent of Cotton Wool Disease of Goldfish:Saprolegnia sp.

​Goldfish with cotton wool disease

Causes of Cotton Wool Disease or Saprolagniasis of Goldfish

  • ​Poor water quality;
  • Improper cleaning of tank;
  • It occurs due to any previous infections, parasites or injuries;
  • Physical injury due to rough handing with hands, nets, containers or sharp decorations;
  • Due to organic matter or uneaten food wastes;
  • Due to rapid changes in water temperature;

Symptoms of Cotton Wool Disease or Saprolagniasis of Goldfish

  • Weak and lethargic movement;
  • Ulceration of exfoliation of the skin following hemorrhage;
  • Blindness;
  • Congestion at the base of the pectoral and anal fins;
  • Inflammation of liver or intestine;
  • Cotton wool growth at the base of pectoral and anal fins;
  • ​Lesions appear as grey patches on various parts of the body like skin, fins, eyes, mouth and gills;
  • ​Color changes to brown or grayish;

Treatment and Preventive Measures of Cotton Wool Disease or Saprolagniasis of Goldfish

  • Avoid rough handling;
  • Avoid overcrowding;
  • ​Improve water quality;
  • You should maintain high quality water in your tank;
  • 20-25% Water changes should be done at regular basis;
  • Removing of uneaten food or dead materials;
  • You should always check the body for any wounds or infection;
  • 5% salt bath for 10 minutes for three days;
  • ​Malachite green 0.2 ppm bath for 5 minutes;
  • Copper sulphate 20 mg per liter of water for 2 minutes;
  • ​Malachite green 1: 10,000 for 3 seconds;
  • ​Also, you can use methylene blue;
  • At the time of treatment feeding should be limited;

Gill Rot Disease of Goldfish

​It is also known as Branchiomycosis. This disease occurs in the blood vessels of the gill tissue. It barricades the blood circulation in the gills and hemorrhage occurs; gills become mottled with patches of brownish discoloration. It disrupts blood flow resulting in necrotic tissue and allows the gills to be invaded by a secondary disorder such as a Saproglenia fungus. A mycotic fungal disease in goldfish is basically connected with stress or damage. Disease with Branchiomyces is quick, and is essentially brought about by algal blooms, over stocking, high water temperatures, and large amounts of ammonia in the tank.

Causative Agent of Gill Rots Disease of Goldfish:Branchiomyces spp.

Causes of Gill Rot Disease of Goldfish

  • ​Overcrowding;
  • High water temperature;
  • Large amounts of ammonia in the tank water;
  • ​Mechanical injury;
  • Stress;

Symptoms of Gill Rot Disease of Goldfish

  • Very lethargic movement;
  • Reparative disorders;
  • Bluish or grayish irregular streaks;
  • Redness in gills, grayish white when attack is severe;
  • ​Dropping of affected gill filaments;

Treatment and Preventive Measure of Gill Rot Disease of Goldfish

  • ​Avoiding organic impure water;
  • Increase water flow to prevent build up of ammonia;
  • Avoiding overcrowding;
  • Good water quality should be maintained;
  • Regulating feeding rate;
  • ​Crape the fungus off;
  • ​Move to fresh water every day;
  • 3-5% salt bath for 5-10 minutes;
  • Malachite green 0.2 ppm bath for 5 minutes;
  • Copper sulphate 20 mg per liter of water for 2 minutes;
  • Malachite green 1: 10,000 for 3 seconds;
  • In addition to salt baths, therapeutic lotions of the following solutions are also used:

– 0.1% potassium permagnate (1 g of crystalline KMnCL per 1 liter of water);

– 0.05% trypaflavine (0.5 g trypaflavin powder per 1 liter of water).

  • ​From the lotions 1.5 – 2% solution of lapis (silver nitrate AgNO3) is better to refuse, because the concentration of the solution is too high.

Bacterial Diseases of Goldfish

​The most common bacterial diseases are ulcer, hemorrhage and septicemia. Many bacterial pathogens causing infection are associated with virus and fungus.

General Causes of Bacterial Diseases of Goldfish

  • Filthy tank condition;
  • Rapid decreases in water temperatures;
  • ​Overcrowding;
  • Corn based diets;
  • Mechanical injury;

General Symptoms of Bacterial Diseases of Goldfish

  • Gray or cloudy eyes;
  • Bulging eyes;
  • ​Skin inflammation;
  • Reddening of skin or fins;
  • White sores are seen on the body;
  • Ragged fins;
  • Swelling;
  • Fungus-like white growth are seen on the body;
  • Rapid breathing;

Tail and fin rot of goldfish

It is well known bacterial disease. It causes erosion and disintegration of fin and tails. Tail or fin rot is normally an optional contamination that may infect your fish.  

Causal Agent of Tail and Fin Rot of Goldfish:Aeromonas spp, Pseudomonas spp, Haemophilus spp.

Goldfish With Fin Rot Disease

​Fin rot of goldfish

Causes of Tail and Fin Rot of Goldfish

  • ​Stress;
  • Poor water quality;
  • ​Overcrowding;
  • Sudden temperature changes;
  • Fin nipping due to aggressive fish;

Symptoms of Tail and Fin Rot of Goldfish

  • Whitening area is seen on the fin margin;
  • ​Lesions develop at the outer fin margin;
  • Frayed and disintegration of soft tissues between fin rays;
  • ​Total fin damages;

Treatment and Preventive Measure of Tail and Fin Rot of Goldfish

  • Judicial stocking;
  • Regulate water temperature and pH;
  • Improving tank environment;
  • Avoiding overcrowding;
  • Oxy tetracycline 50 gm/kg body weight of fish with feed for 5-7 days;
  • Copper sulphate 1:2000 dip for 3-4 days;
  • Oxy-tetracycline with feed daily for 10-15 days;

Columnaris Disease of Goldfish

​It is a contagious and chronic disease and is one of the most likely culprits. It is also called cotton mouth disease. It affects the external structures of the fish body. It is a contamination that hits goldfish, and other pet fish. This disease has a few extremely evident signs and side effects, which can be utilized to quickly recognize it from other goldfish sicknesses. Columnaris can rapidly kill a goldfish, so treatment must be quick.

Causative Agent:Flexibacter columnaris

Fish affected with columnaris disease

Goldfish with Collunaris disease

Causes of Columnaris Disease of Goldfish

  • ​Overcrowding;
  • Poor water quality;
  • Sudden environmental changes;

Symptoms of Columnaris Disease of Goldfish

  • Cottony growth or white threads blowing in and out of mouth;
  • ​Dry skin;
  • Lethargic movement;
  • ​Clamped fins;
  • Skin color becomes darkens;
  • White fungus like or thread like sores;
  • Red anal vent;
  • Mushy belly;
  • ​White sores on the body;
  • ​Show grasping;
  • Tendency to remain the surface and become lethargic;
  • ​Excessive mucus secretion;
  • Various spots on head, back, and caudal fin;
  • Necrotic lesions on the outer edges of affected fins;
  • Secondary fungal infection;
  • Damaged fins;
  • ​Ulcers;

Treatment and ​Preventive ​Measures of ​Columnaris ​Disease of ​Goldfish

  • ​Improve tank management;
  • Avoid overcrowding;
  • Feeding fishes with adequate supplementary feeds;
  • ​Improve water conditions;
  • Frequent water changes;
  • ​Injection of antibiotic if possible;
  • ​Use potassium permanganate in the water;
  • 15% Salt bath for 15 minutes;
  • ​Oxy tetracycline 50 gm/kg body weight of fish with feed for 5-7 days;
  • Copper sulphate 1:2000 dip for 3-4 days;

Dropsy Disease of Goldfish

​Dropsy is the development of liquid inside the body or tissues of a fish. It can show various hidden difficulties, including bacterial diseases, parasitic contamination, or kidney dysfunction. In an aquarium with running water, this disease rarely occurs extremely.

Causal Agent of Dropsy Disease of Goldfish

​Dropsy diseases can occur due to various agents like bacteria (Aeromonas sp, Pseudomonas sp), Virus (Rhabdo virus), and parasites (Myxosporideans)

Dropsy of Goldfish

Dropsy of goldfish

Causes of Dropsy Disease of Goldfish

  • The reason is the poisoning of water by some chemically harmful substance;
  • ​Dropsy in fish also occurs with weakened heart activity, resulting in stagnation of blood, and through the walls of the vessels a liquid is released into the body;
  • ​Dropsy occurs in fish with kidney disease due to the result of an internal bacterial infection in the kidneys. The infected kidneys retain water, become swollen;

Symptoms of Dropsy Disease of Goldfish

  • The lifting of the scales;
  • The eyeballs protrude from the diseased fish;
  • The abdomen is enlarged, the tail and spine flex;
  • Fish cannot keep the body in balance and therefore falls on the bottom;
  • The disease sometimes lasts for months, but always ends in a fatal outcome;
  • ​Inflammation of intestine;
  • Degenerative changes in the heart and kidney;
  • Hemorrhagic ulcers on skin and fins;
  • Ulcer or lesion in the skin and muscle;
  • Swelling;

Treatment and Preventive Measure of Dropsy Disease of Goldfish

  • You should take the diseased goldfish and place it into a quarantine tank for treatment and add 2 teaspoons epsom salt per ten gallons of water to eliminate excess fluids in the goldfish;
  • You can treat with Maracyn Plus Anti-bacteria Therapy or Kanamycin to help treat gram negative bacterial infections;
  • You should feed them with antibacterial food;
  • You should keep the water temperature of the quarantine tank around 25 C ( 77 0 F);
  • Antibacterial treatment with Acriflavine  is very effective to treat the affected fish;
  • Regular water changes should be done and maintain optimal water parameters;
  • Proper handling and proper aquarium set up help to prevent dropsy;

Bacterial Gill Disease of Goldfish

​It usually shows in the gills linked to environmental stress and it is well known bacterial disease. It occurs when filamentous bacteria is present on the gills. Generally this disease is caused due to poor water quality, low dissolved oxygen content and overstocking.

Causal Agent of Bacterial Gill Disease of Goldfish:Flavobacterium branchiophilum (gram negative non-motile bacilli)

Causes of Bacterial Gill Disease of Goldfish

  • ​Overstocking;
  • ​Low water quality;
  • ​Low dissolved oxygen content;
  • Raising ammonia, nitrate and nitrites level;

Symptoms of Bacterial Gill Disease of Goldfish

  • Grasping;
  • Swelling of opercula;
  • Mats of bacterial growth on gill surface;
  • Frayed appearance of gills;
  • ​Lethargic movement;
  • Fish does not eat all;
  • White streaks are seen on gills;
  • Edges of gills become whitish in color;
  • Gill covers become pale;
  • Gill arches break down;

Treatment and Preventive Measures of Bacterial Gill Disease of Goldfish

  • ​Improve tank environment;
  • Avoid stressful conditions;
  • Treat with potassium permanganate, Chloramines-T or Copper sulphate;

Inflammation of the Stomach or Gastroenteritis of Goldfish

  • This disease occurs when overfeeding with poor-quality food and also during long-term feeding with dried daphnia, gammarus and bloodworm, which are poorly absorbed by the body and cause inflammation of the gastrointestinal tract of fish.
  • The lack or absence of plant foods also contributes to inflammatory processes.

​Symptoms of Gastroenteritis of Goldfish

  • The activity of the fish decreases;
  • Loss of appetite;
  • The stomach swells slightly;
  • The anal opening becomes red in color;
  • The filthy excrement with bloody mucus is seen;

Treatment and Preventive Measure of Gastroenteritis of Goldfish

  • The disease is easily treated with starvation within a week.
  • The fish is transferred to an insulator with fresh water with the addition of a weak solution of potassium permanganate.
  • ​It is necessary to raise the water temperature by 2 – 3 0C and increase the aeration.
  • 10-15 % water change should be done regularity.

Swim Bladder Disease of Goldfish

​Swim bladder illness or flipover, is a typical sickness in aquarium fish such as goldfish. The swim bladder is a gas-filled internal organ that helps the goldfish remain stable in the water without wasting strength in swimming. This organ makes the goldfish more light and it leads towards the surface. Swim bladder illness is the point at which a fish loses its capacity to manage the air going all through its swim bladder.

Swimm bladder disease of goldfish

​Swim bladder disease of goldfish

Causes of Swim Bladder Disease of Goldfish

  • ​Due to constipation;
  • Due to drastic changes in water temperature;
  • Due to bacterial or parasitic infection;
  • Due to rapid changes in water pH;
  • ​Due to high level of nitrates;
  • Poor quality feed;
  • Gulping air during feeding at the surface with dry floating foods;
  • Mechanical injury;
  • Genetically deformities;

Symptoms of Swim Bladder Disease of Goldfish

  • Affected fish cannot keep its position in the water;
  • Fish either goes to the bottom;
  • They float to the surface of the water, often up-belly;
  • They don`t eat food at all;
  • They swim upside down;
  • They have inflated belly;
  • They may have curved spine;
  • They float near the surface;
  • They swim with tail higher than head;
  • They cannot swim easily;
  • They sink to the bottom and struggle to rise up;

Treatment of Swim Bladder Disease of Goldfish

  • There is no effective method of treatment;
  • You should lower the water level to reach the surface easily;
  • You should slight increase the water temperature;
  • You should stop feeding for 3 days and then feed those skinned peas or veggies and fruit with small quantities;
  • Good results are provided by the normalization of conditions of aquarium;
  • Tank environment should be cleaned;
  • Finally you may use broad spectrum antibiotic;

White spot disease or Ich of goldfish

​It is also known as Ichthyopthiriasis. It is one of the most common diseases of goldfish. It is also, unfortunately a very persistent disease. It infects different parts of the body externally. Ich disease is caused by a protozoan parasite (Ichthyopthirius multifiliis). This parasite is easily introduced into your aquarium during introduction of new fish or equipment. This parasite generally enters the fish body surface and feeds on its tissue and blood. The white spots that seem look like grains of salt or sugar, however everyone is really a little parasite. They are extremely harming to the fish and can bring about breathing and portability issues and even death.

Causal Agent:Ichthyopthirius multifiliis

Fish with white spot disease

​White spot disease of goldfish

Causes of White ​Spot ​Disease or Ich of ​Goldfish

  • Rapid drop in water temperature;
  • ​Due to introduction of new fish or equipment;

​Symptoms of White ​Spot ​Disease or Ich of ​Goldfish

  • Presence of small whitish cysts on the skin, gills and fins;
  • Necrossis;
  • Lifting and separation of respiratory and skin epithelium;
  • Typical gill like white cysts/small tubercles on skin;
  • Heavy breathing;
  • Swim to tank surface;
  • Protruding eyes;
  • Unsettled swimming;
  • Ulceration;
  • ​Gills damage;

Treatment and Preventive Measure of White Spot Disease of Goldfish

  • Pre-treatment with 2-3 % salt bath;
  • ​Regular water exchanges;
  • Raise of the tank water temperature and it should be between 20-25 °C (68-77°F);
  • ​High oxygen levels should be maintained;
  • Maintain balanced pH level;
  • Before introduction into tank quarantine of new fish should be done for two weeks;
  • You should boil new ornaments and stones before placing in tank;
  • Removal of infected fish;
  • ​Improve tank environment;
  • ​Potassium permanganate 2.5 ppm for two successive doses;
  • ​Formalin 150 ppm for an hour with continuous aeration;
  • Mlachite green oxalate 0.15-0.2.0 ppm for 4-6 hours for 4 times at 2 days intervals;
  • Quinine 1:50000 for 3-7 days;

Anchor Worm Disease of Goldfish

It is caused by copepods parasite Lernaea spp.  Anchor worm disease is also known Lernaeasis. Lernaea is a rod like external parasite which may attach the host goldfish anywhere of the body. Generally this copepod affects the pectoral and dorsal fins which is visible to the naked eyes.

Causal Agent:Lernaea spp.

Anchor worm disease of goldfish

​Anchor worm disesae of goldfish

Causes of Anchor Worm Disease of Goldfish

  • ​Due to introduction of new fish or equipment;
  • Newly added plants that can have larvae on them;

Symptoms of Anchor Worm Disease of Goldfish

  • Loss of weight and hemorrhage;
  • Ulceration;
  • Inflammation on the body of the fish;
  • General lethargic movement;
  • Frequent rubbing against wall of the tank or any decorations;
  • Fish become lethargic and weak;
  • Excess mucus secretion from skin, fins and gills;
  • Lernaea are seen in eyes, gills, operculum, lips and other body surface;
  • Breathing difficulties;
  • Ulcers;

Treatment and Preventive Measures of Anchor Worm Disease of Goldfish

  • Total dewatering of infected tank;
  • Remove the worms using tweezers, grip;
  • Check the entry of free swimming fry goldfish;
  • Regular changes of water;
  • ​Proper tank management should be taken;
  • ​Potassium permanganate 5 ppm bath;
  • ​Gammexane 1 ppm;
  • Dipterex 0.2-0.5 sprinkling over the water surface at least three times at three week intervals;
  • ​Potassium permanganate 30 ppm for 20 minute twice a day for 5 consecutive days;
  • Formalin 150-250 ppm solutions;
  • Trichloroform 5 ppm bath for 10 minutes or 15 dip for 20 minutes four times at weekly intervals;
  • Salt 3-3% dip for 30 seconds -1 minute;
  • Chlorine 1ppm for 3 days;

Fish Lice Disease of Goldfish

​Fish lice is a crustacean parasites which affects goldfish and cause fish lice disease. It is also known as argulosis. Fish lice or Argulus has flat and rounded body with sucking and piercing type mouthparts. It is also a vector for various pathogens such as bacteria, fungus etc which is responsible for epizootic outbreaks that leads to collapse of your aquarium inhabitants.

Causal Agent of Fish Lice Disease of Goldfish:Argulus spp.

Fish lice disease of goldfish

Fish lice disease of goldfish

Causes of Fish Lice Disease of Goldfish

  • ​Due to introduction of new fish or equipment;
  • Newly added plants that can have larvae on them;

​Symptoms of Fish Lice Disease of Goldfish

  • ​Loss of scale;
  • Appearance of red spots at the infection sites wit circular depression;
  • Agitated swimming;
  • Scraping against the substrate;

Treatment and ​Preventive ​Measures of Fish lice ​Disease of ​Goldfish

  • Removal of hard substrate including submerged vegetation and concrete structure;
  • Dewatering of tank;
  • Removal of fish lice using hand;
  • Sumithion 0.25 ppm;
  • Malathion 0.25 ppm;
  • ​Dipterex 0.50 ppm at twice weekly intervals;
  • ​Potassium permanganate 30 ppm for 10 minutes;
  • Aquarium salt 3-5% solution for 30 seconds-1 minute dip;
  • Ammonium chloride 500 ppm;

Cold ​Attacks ​On ​Goldfish

​Generally goldfish are not prone to colds. During transportation if sudden fluctuations in the temperature of the water occur cause colds. A significant temperature difference causes irritation of nerve endings. As a result, functional disorders of the body occur.

​Symptoms of Cold Attacks on Goldfish

  • Exfoliation;
  • Necrosis of the skin;

Treatment and ​Preventive ​Measures of Cold Attacks on Goldfish

  • Temperature differences should not be tolerated;
  • Increase the temperature of water by 2 – 3 C with the addition of methylene blue;
  • ​Enhance aeration;
  • Abundant feeding with plant food and a variety of live food. In this case live food must be well-washed;
  • ​With this disease, before giving fresh frozen foods (bloodworm, ​Corethra, ​Daphnia) should be warmed;

Read Also: How to Set up an Aquarium


Goldfish illness is very common today. They are influenced by different illness due to environmental stress followed by parasitic, fungal, viral, bacterial or protozoan infections which can cause early death. For treatment purposes, finding of diseased fish is an essential part  to care goldfish against diseases.  If you can early recognize the symptoms and give appropriate treatment to your diseased fish, your fish can make a totally recovery. In this case, medication should be done precisely with prescribed dosages. In addition to goldfish,  Zebra Danio (Danio rerio) can also make your aquarium stunning.

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