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Freshwater Fish Diseases

Freshwater Fish Diseases

Freshwater fish are always prone to diseases over a prolonged period of time. It is necessary to understand the causes and symptoms, so that proper treatment can be provided. These diseases can be avoided by regularly cleaning the aquarium and treating the water with medicine. Here's more...
PetPonder Staff
Freshwater fish constitute 41% of the known species of fish. They dwell in freshwaters like lakes and rivers, where the salinity is as less as 0.05%. Most of them make good aquarium fish. But these fish are quite prone to diseases.
Fish Health Issues
Most of the tropical fish diseases are due to bacterial, fungal, protozoan or parasitic infections. External factors like lack of oxygen or chemical poisoning and physical wounds can also result in infections. Read on below for more information on freshwater fish diseases.
Disease: Fish Fungus
Infection Type: Fungal
Symptoms: Gray colored or white colored growths appear on the scales of the fish. This fungal infection is caused by water molds. The most common water mold that affects fish is a filamentous fungi known as saprolegnia. This infects the fish by secreting digestive enzymes on the tissue of the body, thereby absorbing all the nutrients of the fish.

Treatment: Medications like Jungle Labs Binox Crystal can be used to protect the fish from such fungal afflictions. Cleaning and recycling the aquarium water is advised.


Disease: Ichthyophtirius/White spot/Ich
Infection Type: Protozoan
Symptoms: This is a protozoan infection caused by protozoa Ichtyopthirius. Symptoms can be identified by the development of small white spots on the fins and skin of the body. This gives an appearance of salt coating on the body of the fish. The protozoan primarily starts feeding on the epithelial tissues of the fish gills. It rapidly multiplies by binary division. Betta fish are most susceptible to this protozoan infection.

Treatment: To prevent any further multiplication of Ich protozoan, it is important to maintain the water at a temperature 25 - 82 º F. The increase in temperature speeds up the life cycle of the protozoan, thereby mitigating its multiplication. Medications containing copper and malachite green are recommended. Water treatments like Aquarisol are also given to eliminate protozoans causing infections.


Disease: Fin Rot
Infection Type: Bacterial
Symptoms: Symptoms like loss of appetite, inactivity, and rotting fins can lead to believe that the fish is suffering from the infection of fin rot (caused by Pseudomonas fluorescens).

Treatment: The main reason for this infection is smutty water conditions. Clean the water regularly and remove any carbon content before using any kind of medication, as carbon absorbs the medication. Antibiotics like tetracycline, penicillin, amoxicillin or erythromycin can be used for treatment.


Disease: Malawi Bloat/Dropsy
Infection Type: Bacterial
Symptoms: This bacterial infection is diagnosed by signs of swollen abdomen, lethargy and discoloration of fish.

Treatment: Proper fish food is an important part of care, because Malawi bloat is often caused by malnutrition as well. To prevent further bacterial infection, water change must be done on a regular basis.


Disease: Pop-Eye
Infection Type: Bacterial
Symptoms: As the name suggests, the eyes of the fish bulge out due to fluid accumulation. If the symptoms are overlooked, the fish may start looking gross. Goldfish are the most common fish to get afflicted with pop eye disease.

Treatment: In such cases, the fish can be quarantined. A natural cure that can slow down the infection is adding Epsom salt to the aquarium water. The ratio must be 1 tablespoon of Epsom salt for 5 gallons of water. A 50% water change is mandatory to prevent further aggravation of the bacterial infection. Antibacterial treatments such as maracyn and esha 2000 are also recommended.


Disease: Swim Bladder Disease
Infection Type: Parasitic
Symptoms: Swim bladder is an internal organ of the fish that helps it to float in normal depth without having to swim for long. Basically, it promotes the buoyancy factor. When the swim bladder gets infected, the signs of swim bladder disease become apparent, with the fish not moving much. They usually tend to stay at the bottom of the tank or float on the surface.

Treatment: 10% water change a week is recommended. To combat the infection and improve the digestion process, fish are fed with peas.


Disease: Head and Lateral Line Erosion - HLLE
Infection Type: Bacterial
Symptoms: The symptoms of this infection can be identified by the appearance of small gray lesions that start around the eyes and head, and spread all the way across the lateral line of the body.

Treatment: Fish must be fed with rich vitamin supplements containing vitamin A, vitamin C, and vitamin D. Also, the water must be devoid of carbon particles which can aggravate the lesions by irritating the skin of the fish.


Disease: Velvet (caused by oodinium parasite)
Infection Type: Parasitic
Symptoms: This resembles Ich. However, the signs of velvet become apparent with the appearance of yellow or gray dusty spots on the skin of the fish. Infected fish usually have the tendency to flap their gills rapidly and rub them against the glass of the tank.

Treatment: Water should be diluted with copper salt. Aquarisol is recommended for the treatment of this infection.


Disease: Oxygen Starvation
Infection Type: External Factors
Symptoms: The fish might frequently swim up to the surface and gulp down water. This indicates there is not enough oxygen in the tank.

Treatment: Aeration needs to be increased within the tank. This can be done by adding some aquarium furniture like airstones and powerheads to the tank, to increase the flow of the filters. If the temperature of the water is higher than normal, add a few ice cubes to the tank.


Disease: Ammonia Poisoning/Nitrate Poisoning
Infection Type: External factors
Symptoms: The first sign of ammonia/nitrate poisoning is the deep red coloration of gills. The gills also might swell due to the poisoning. The fish might exhibit traits of lethargy and might frequently swim up to the surface gasping for oxygen.

Treatment: Water change is the immediate step to be taken. About ⅓ water has to be recycled. Cleaning and filtering the aquarium on a regular basis is very important.


Fish Care
The above mentioned are some of the common aquarium fish diseases. They are curable with proper remedies and treatments as stated above. Whenever a health issue is identified in a fish, the first action should be to isolate the fish to prevent a contagion. The infected fish can be put in an isolated hospital tank where the water is diluted with medication salts like Epsom salt or formalin. Once the fish gets better, it can be moved back to its original tank. But before you do that, make a point to disinfect the tank with potassium permanganate. At times, heat therapy is also suggested as an effective treatment for parasitic and fungal infections.