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Bacterial disease in fish

Bacteria• Unicellular 0r Single celled microscopic organisms.

• Cell membrane made up of cellulose and chitin.

• Vacuoles.

• Gram-positive and negative .

• Cell walls are thick and thin .

• Lack nuclei and other organized cell structure.

• Some bacteria are pigmented .

Bacterial diseases in fish1) Furunculosis2) Columnaris3) Dropsy4) Vibriosis5) Tuberculosis6) Bacterial gill disease7) Fin rot/tail rot

Common symptoms lethargic swimmingLoss of appetiteRespiratory distressJumping from the waterColour of gill changedFins become frayed

CAUSE Poor water qualityFluctuation in temperatureImproper nutritionAccess waste deposition

Furunculosis• Causative agent - Aeromonas salmonicida

• Furunculosis is highly contagious disease that affects fish of all ages.

• The infection causes high mortality in salmonids, though some other species of fish are affected.

• Horizontal transmission occurs via the water column, but also through direct fish-to-fish contact and animal vectors.

Pathological sign 1) Furuncles (or boils) involving skin and/or

muscle progressing to lesions.2) Haemorrhages on the skin, mouth and

fin bases.3) Darkening of body colour and pale gills.4) Bloody discharge from nares and/or vent. 5) Stomach filled with mucus,

blood.

TREATMENT• To drain the pond and treat it

with slaked lime.

• Treatment is done by removing the severely infected fishes from the pond and by supplying food containing antibiotics like introfurans or sulphonamids etc.

• Disinfection may be done with 0.015 % sol. of merthiolate or 0.185 % sol. of Acriflavin . 1% provindone-iodine sol. is most recommened ones owing to its relatively lesser toxicity compared to other disinfectants.

• Iodine is used to decontaminate the surface of fertilised eggs to prevent vertical transmission (passage of infection from parent to offspring).

columnaris (cotton mouth)•Causative Organism: Flexibacter

columnaris/Chondrococcus columnaris

•Often mistaken for a fungal infection because of its mold-like lesions.

•Columnaris is a common bacterial infection in aquarium fish, particularly livebearing fish and catfish.

symptoms•White spots on mouth, edges of scales,

and fins.•Fins disintegrate beginning at the edges. • 'Saddleback' lesion near the dorsal fin.

Treatment •Add antibiotic in water .

•Normally used antibiotics include the chloramphenicol ( 10 ppm. repeated at 2-5 days interval ) and furance ( o.1 – 0.3 ppm ) in which the infected fishes with cotton mouth disease are kept for a long time bath.

Infectious Dropsy •Causative agent- Pseudomonas punctata

•Dropsy is an old medical term that was once used to describe swelling due to accumulation of fluids in the tissues or body cavities, such as the abdomen. Fish suffering from Dropsy often have a hugely swollen belly.

• It was the most feared disease in carp culture

Symptoms •Swollen belly.•Scales stand out.•Eyes bulge.•Anus becomes red and swollen.•Internal organs are affected, most notably

the liver and kidneys.• Spine may become curved.•Fish hangs near the surface.

Treatment •Removal and complete destruction of fishes ,

followed by draining , drying and disinfecting the fish pond with quicklime is suggested to prevent spread of the disease.

•The infected fishes may be cured by a two minutes dip in 5 mg / KMnO4 sol.

•Resistant strains bacteria may be killed by applying streptomycin or chloromycetin or oxytetracyclin along with supplementary food or by injecting the severely infected fishes .

vibriosis•Causative agent – Vibrio anguillarum•This is comma shaped bacterium. •It enters the animal via their food and

attacks the gastrointestinal tract.• found in all species in saltwater •It multiplies in the skin of salmonids, but

the toxins produced act on the circulating blood cells causing severe anaemia.

•This disease occurs more than readily at temperture above 11°c.

symptomsLarge bright colour body lesions in the

skin and muscles.Gills may bleed with slightly pressure.Inflammation of intestinal tract.Eye problems with cloudy eye, leading to

pop-eye and finally eye loss.

Treatment •Dip treatment in copper sulphate sol. and

application of antibiotics with artificial food may be considered as curative measures for vibrosis

TUBERCULOSIS•Causative agent- Mycobactrium piscium.•A bacterium closely related to

Mycobacterium tuberculosis called Mycobacterium piscium can be present in wild caught as well as captive bred fish and stay lurking in our aquariums without us ever realizing it.

• Fish can be treated with the same drugs as humans get when they become infected by Mycobacterium piscium, e.g. Kanamycin.

SYMPTOMS Fin rot , waxy coat on body , ulcer on

body.o Nodules in the internal organs

loss appetiteLoss body weight•Loss of scalesLoss of colours

Treatment

•Dip treatment for one minute in 1 : 2000 copper sulphate sol. for 3-4 days may be useful.

•Alternatively the fishes may be destroyed and the pond sterized with KMnO4 or with soaked lime restocking .

Bacterial gill disease•Causative agent- Myxobacteria

• The colonization of damaged gills by these organisms in the condition known as

“BACTERIAL GILL DISEASE”

• This reduces the ability of the gills to supply oxygen to the blood and results in mortality if left unchecked.

symptoms Swelling in gill lamellae. Change in gill colour.

Treatment •Application of antibiotics like neomycin

chloramphenicol etc. may be useful in treatment of bacterial gill disease in fishes .

Fin rot / tail rot•Causative agent- Myxobacteria •Fin Rot is one of the most common.

•It is caused by several types of bacteria and often occurs concurrently with other diseases.

SYMPTOMS•Fin edges turn white•Fins fray•Bases of fins inflamed•Entire fin may rot away

TREATMENT•Move sick fish to a hospital tank.•Feed fresh high quality foods.•Treat with antibiotics(MARACYN-2, a ten day

course is ideal for ensuring the infection is eradicated)

•Terramycin has proven to be quite effective both as a bath, and when used to treat foods for internal infections.

preventionsi. Perform regular water changes.ii. Keep the tank clean.iii. Clean the filter regularly.iv. Avoid overcrowding the tank.v. Use flake foods within one month of

opening.vi. Use disinfect nets and other equipments.

•If the tank is well maintained, and the fish fed a healthy diet, outbreaks of any bacterial disease are unlikely..