A Complete Guide to the Prevention and Treatment of Common Diseases in Ornamental Fish

Disease prevention and treatment in ornamental fish should adhere to the principle of "prevention first, treatment second, prevention is more important than cure." In home care for ornamental fish, the first-choice remedy is table salt, which is convenient, economical and easy to measure. Let's take a look below at the complete guide to preventing and treating common diseases in ornamental fish!

Fungal Diseases in Ornamental Fish

1. Skin mold disease (water mold disease)

[Cause] An extremely common ornamental fish disease. During capture or transport, the fish body suffers external injury, or parasites wound the fish's skin, after which mold spores invade and cause infection.

[Pathogen] Aquatic molds such as Saprolegnia and Achlya.

[Symptoms] White fuzz grows on the fish's body. In severe cases the white fuzz can wrap around the entire body. The fish becomes thin and weak and its swimming ability decreases. This disease can occur in all four seasons.

[Prevention] As long as you are careful during capture and transport so the fish body is not injured, you can add a small amount of table salt to the aquarium holding new fish to inhibit the occurrence of water mold, pay attention to cleaning and disinfection when adding live bait, and keep the water clean to cut off the growth of water mold. Generally this can prevent the disease. If it does occur, the following treatment methods can be used.

[Treatment] ① Soak in 2%-3% salt water, once a day, 5-10 minutes each time. ② Soak in a 1-2 ppm malachite green solution, a specific remedy, for 20-30 minutes daily. ③ Mix 2 ppm potassium permanganate with 1% salt water and soak the diseased fish for 20-30 minutes. ④ Raise the water temperature to inhibit the growth of water mold. Also, a 15-watt ultraviolet lamp can be used for several hours daily to effectively inhibit and destroy water mold.

2. Gill mold disease

[Pathogen] Fungi of the genus Branchiomyces.

[Symptoms] When the spores of the fungus are scattered in the water, they encounter the fish's gills, attach to them, invade the tissue and grow. When the fish is found to have difficulty breathing, opening the gills will reveal the fungal hyphae.

[Prevention] Again, prevention means keeping the water clean. Inhibiting the growth of the fungus can avoid the occurrence of this disease.

[Treatment] Treatment can refer to the treatment methods for water mold disease.

Viral Diseases in Ornamental Fish

Viral diseases are extremely dangerous among ornamental fish diseases. They are troublesome to treat, spread quickly and have a high mortality rate.

1. Black death disease

[Cause] Gram-positive bacterial infection complicated by intestinal parasitism by hexamita.

[Pathogen] Hexamita and enteritis-like drug-resistant bacteria.

[Symptoms] The fish's fins fold together, the body twitches, it cowers and fears people, the body color turns black, appetite slightly decreases, it hides in the corner of the tank, gradually loses appetite, the fins become damaged and ulcerated, a cloud-like ulceration appears on the body surface, covered with many white protrusions, the tail and fins clamp, it loses balance and finally dies.

[Treatment] ① Improve water quality, such as by changing water or adjusting the pH value. ② The specific remedy Black Namin. ③ Alternate use of Black Namin and Helishamin.

2. Hemorrhagic fever

[Pathogen] Herpesvirus.

[Symptoms] The diseased fish's body surface turns black and lusterless, and the mouth, fin rays and muscles are congested. Sometimes the gill cover, head and abdominal wall are congested, the gill filaments show bright red spotted or patchy congestion, and in severe cases the gills lose blood and become pale, turning into "white gills." The eyeballs may show bulging symptoms (this bulging symptom is different from the exophthalmia of arowanas). The disease season is mostly from June to September, and it is most prevalent when the water temperature is 26-30 degrees Celsius.

[Treatment] ① Give sufficient sunlight exposure and try to lower the water temperature to below 25 degrees Celsius. ② Bathe in a water bath of an extract of the Chinese herb rhubarb. ③ Grind 0.25-0.5 grams of rhubarb and sweetgum leaves into powder, decoct them, mix with beef heart hamburger and feed, while adding a 0.6 ppm solution of Yeqingling to the aquarium for two consecutive days. ④ Soak with antibiotics (such as penicillin, erythromycin, etc.).

Bacterial Diseases in Ornamental Fish

Bacterial diseases are the most numerous among fish diseases caused by bacteria. Common ones include gill rot disease, bacterial enteritis, white skin disease, scale protrusion disease, hemorrhagic putrefaction disease, stamp disease, furuncle disease, white head and white mouth disease and several others. They are all relatively common ornamental fish diseases, and when they occur they are generally quite dangerous.

1. Gill rot disease

[Pathogen] Myxococcus piscicola

[Symptoms] The fish's gills are full of mucus, and bleeding occurs on both the gill filaments and the inner epidermis of the gill cover bone. The gill filaments quickly turn from red to white, gradually rot, and finally the entire gill rots away, causing the fish to lose its respiratory function and die.

[Treatment] ① Bathe in a 12.5 ppm nitrofurazone solution for 30 minutes. ② Bathe in a 12.5 ppm oxytetracycline solution for 30 minutes. ③ Repeat daily until the diseased fish recovers, and at the same time clean all equipment and the aquarium with a 1 ppm nitrofurazone solution to disinfect and prevent the fish from being infected again.

2. Bacterial enteritis

[Cause] Eating unclean food, or overeating, intestinal bloating, blocked excretion, leading to bacterial infection of the intestinal tract and causing enteritis.

[Pathogen] Aeromonas punctata.

[Symptoms] The diseased fish stays motionless in the corner of the aquarium and does not eat, the abdomen swells with red spots, and the anus protrudes. The muscles twitch briefly, the feces are white. If a necropsy is performed, abdominal dropsy is found, the intestinal wall is congested and inflamed, and in severe cases the intestines are purplish red with no food inside, only pale yellow mucus and thick blood.

[Treatment] Oral medication mainly includes Yufukang, sulfaguanidine, Nakejun, etc. For bathing, nitrofurazone, gentamicin, oxytetracycline, furazolidone, etc. are used. Oral medications must be dissolved and mixed into beef heart hamburger or other mixed bait for feeding. If the fish can no longer eat, then only bathing is possible (some also use intramuscular injection of gentamicin and penicillin).

3. White skin disease (also called white tail disease)

[Cause] The aquarium is unclean, especially if fish feces are not cleaned up in time, or careless handling during capture and transport injures the fish and causes pathogenic bacteria infection (showing the harm of external injury).

[Pathogen] Gram-negative bacillus of Pseudomonas dermoalba

[Symptoms] Small white spots appear on the dorsal fin or caudal fin, or possibly at the base of the dorsal fin plus caudal fin (that is, the fish's back and caudal peduncle). The white spots rapidly expand until the entire caudal fin turns white and rots away. The diseased fish's swimming ability is markedly reduced, it loses balance and may stand upright swimming vertically up and down, and dies in 2-3 days. The mortality rate is extremely high. This disease is prevalent from May to August.

[Treatment] Bathe in a 25 ppm oxytetracycline or chlortetracycline solution for 30 minutes/day, and disinfect the aquarium with a 1 ppm bleaching powder solution.

4. Scale protrusion disease

[Pathogen] A bacterium similar to Pseudomonas punctata.

[Symptoms] The fish's scales change from lying flat against the body surface to spreading outward one by one like a pine cone. The scale pouches at the base of the scales become edematous, and a light press on a scale causes it to fall off. The diseased fish dies after 2-3 days. This disease is not contagious. It is mostly seen in goldfish, koi, Anabantidae fish and ovoviviparous killifish such as mollies, moonfish and guppies. It is more prevalent every spring.

[Treatment] ① Bathe in a 1:50,000 tetracycline solution for 1 hour/day. ② Bathe in a solution of 2% table salt plus 3% sodium bicarbonate for 10 minutes/day. ③ Soak in a nitrofurazone plus furazolidone solution.

5. Hemorrhagic putrefaction disease

[Cause] Caused by pathogenic bacteria invading after the fish body is injured. In winter, if the fish suffers frostbite, this is also a major cause.

[Pathogen] Gram-negative bacterium of Pseudomonas fluorescens.

[Symptoms] Bleeding and inflammation of the body surface, shedding of scales, congestion of the dorsal fin or all fins, the fins rot like a broken fan, water mold develops at the sites of lost scales or rotten fins, and it may occur together with gill rot and hemorrhagic disease (see viral diseases).

[Treatment] Soak in 1% salt water, or 2 ppm potassium permanganate, or a 2 ppm bleaching powder solution.

6. Stamp disease (also called rotten skin disease)

[Cause] This disease occurs when water quality is unclean or the fish body is injured. There is no obvious seasonal distinction.

[Pathogen] The punctata subspecies of Aeromonas punctata, also a type of Gram-negative bacterium.

[Symptoms] Near the anus or on the caudal peduncle (rarely on the front part of the fish body), the skin and muscles become inflamed like an abscess. The muscles gradually rot away, forming a round or oval lesion, as if branded with a stamp.

[Treatment] Refer to the treatment methods for other Gram-negative bacteria.

7. Furuncle disease

[Pathogen] A type of Aeromonas punctata, belonging to the Gram-negative bacteria.

[Symptoms] Inflammation of the subcutaneous muscle tissue, with ulcer-like abscesses and edema. The abscesses contain large amounts of pus, blood and bacteria. The base of the fins is congested, the fin rays split, and in severe cases the intestines are also congested.

[Treatment] Refer to the treatment methods for other Gram-negative bacteria.

8. White head and white mouth disease

[Pathogen] A type of Myxococcus, similar to the pathogen of gill rot disease. The optimum temperature is 25 degrees Celsius, and the pH value is between 6-8.5.

[Symptoms] The cells of the diseased fish's forehead and around the mouth necrose and turn white, ulcers form, sometimes with grayish-white downy material. The body becomes thin and black. The disease comes on extremely quickly and spreads rapidly, and all may die within a single day. It is mostly seen from late May to early July.

[Treatment] Sprinkle a 1 ppm bleaching powder solution into the aquarium for disinfection.