Bacterial infections in fish and ornamental fish all info and details

Bacterial infectionsNote: Please note that this page treats all information without guarantee and has no guarantee for correctness. Furthermore, online information does not replace a visit to the veterinarian. For any questions about medications, treatments, diseases or applications, we recommend consulting a veterinarian about.

The contents presented do not constitute a recommendation or promotion of the diagnostic methods, treatments or drugs described or mentioned. The text makes no claim to completeness, nor can the timeliness, accuracy and balance of the information presented be guaranteed. We ame no liability for any inconvenience or damage resulting from the application of the information presented here.

External symptoms

– skin ulcers, mostly with red border – reddened and inflamed body parts – bleeding on skin, gills and fins – reddened fins – frayed fins – protruding scales – goggle eyes – swollen abdomen – emaciation – black body parts


– Sluggishness – Inability to eat

Internal symptoms

– Bloody fluid in abdomen – Wounds on internal organs – Bleeding on internal organs and musculature


Chela dadyburjori (Dadyburjor's keelbelly danio) with severe redness indicating possible bacterial infection.

Red of Rio with red spots on the abdomen, indicating an internal bacterial infection. Side effects were fin rot and goggle eyes. streak catfish with fungal infection. Bacterial infection on the antenna. The feeler turns white. The transition between white discolored. Normal colored part was inflamed red. A fungus ball formed around the feeler. The discolored part of the antenna fell off shortly after the photo was taken.

Photo: Andre Hamscher

Photos: Frank Staudenmaier

Sumatran barb with inflamed gills, possibly caused by parasites or gill worms.

White Black Molly with inflamed pop-eye. Cause is probably an injury.

Death due to severe bacterial infection

Apistogramma agassizii with bacterial infection. The fish died shortly after ingestion.

Loach with bacterial infection. Next to the open spot there is another swelling resp. bump under the skin, which is barely visible in the picture.

Apistogramma macmasteri female with thyroid tumor or internal bacterial infection. The female died from the disease.

Pelviachromis pulcher with thyroid tumor or internal bacterial infection

Corydoras trilineatus with red belly and fin rot due to a bacterial infection

Pufferfish with internal bacterial infection

A gourami with bacterial infection. Corresponding symptoms are also common with the dwarf gourami disease.

A white coating appeared on the side of a flounder eel in the same aquarium at the same time. Evtl. also caused by a bacterial infection.

Goldfish with bacterial infection

Goldfish with severe bacterial infections

The discoloration on the belly could indicate an internal bacterial infection. Possibly the infection was caused because the fish was kept in fresh water in the trade, although it needed brackish water. The puffer died shortly after the photos were taken.

Corydoras trilineatus with bacterial infection. After treatment with nifurpirinol, the red inflammatory foci receded in four out of five affected animals. Originally, one animal had become conspicuous because it pinched its tail fin together. When viewed with a magnifying glass, some irregular red dots were visible under the scales. These were about 0.5 mm in size and looked like increased blood flow or small inflammation. Skin and scales looked normal and unharmed.

Photos: Viola (Forum)

Wedge spotted tetra with bacterial infection, recognizable by the red spots. After treatment with antibacterial agents the fish became healthy within a few days.

Photos: Sonja (Forum)

Copper tetra with bacterial infection, recognizable by the slightly red bump. A second copper tetra developed a pop eye and a small, white and fluffy coating in one spot. The coating also turned red shortly after. The tetras were treated with Furanol lt. Package insert treated. The bump formed back. The area was only slightly gray. The other tetra died.

Photos: Heinz Gaugenrieder

Featherbeard catfish with whitish mouth. On both sides of the body the animal had small holes. At least on the pictures the area in front of the tail root seems to be reddened. Symptoms indicate a bacterial infection, evtl. Columnaris, hin.

Photos: Manadis (Forum)

Star-spotted tetra with internal bacterial infection. tetras in the affected aquarium became paler and almost milky, got distended bellies, pop-eyes. In the case of the star-spotted tetras, the insides were seen to have a reddish tinge to them. Little by little the animals ate less and less, encapsulated themselves and died approx. 2 days later. At the same time in another aquarium probably the False Neon Disease appeared, also a bacterial infection. Other fish species were not affected. The cause was probably an increased susceptibility of the tetras due to hard aquarium water with 13°gH and 8°kH after a relocation.

Photos: Detlef Beyer

Corydoras with presumably bacterial infection. The blisters are probably filled with fluid, which is the result of the bacterial infection. Similar blisters can be caused by sporozoa or worms. The exact cause can only be determined by cutting open the blisters and, if necessary, by a microscopic examination. a microscopic examination of the contents can be determined. Indications give the origin. Keeping time of the affected fish. Bacterial infections are very likely to occur in fish that have been bred and kept in their own aquariums for a long time. Worms very unlikely.

Photos: Michael Einar Reynis

fish with bubbles on the head. The white coating on the middle bubble could be caused by a fungus. On the photo it is not recognizable whether it is longer fungal threads or a bacterial coating. In connection with the blisters it can be amed that it is a bacterial infection. The blisters are probably filled with liquid, which is caused by the bacterial infection. Similar blisters can be caused by sporozoans or worms. The exact cause can only be determined by cutting open the bubbles and possibly. a microscopic examination of the contents could be determined. Clues give the origin. Keeping time of the infected fish. In fish from offspring that have been kept in their own aquarium for a long time, a bacterial infection is very likely and sporozoa or. Worms very unlikely.

Photo: Thomas Boening

Red neon tetra with white spots. Such sharply defined white dots are probably harmless bacterial colonies that form on slightly damaged skin areas. Usually strong water changes are sufficient, so that the points disappear. In addition easily antibacterial means can be used, like sea almond tree sheets, alder cups etc.

Photos: Lisa Schellauf

After being housed in a transition tank, two neon tetras from a group of neon tetras looked like shown in the photo. Other fish were not affected. The affected animals ate normally. Were normally integrated in the shoal. The tetras coped with a two-hour transport in the car without any problems. The symptoms had been visible for several months when the photo was taken.

White coating is often caused by bacteria from the Columnaris environment. The white nodules could also be bacterial colonies. The white nodes are also similar to the symptoms on Red Neon, which are classified under bubonic disease.

The spines of the affected neons were bent just before the caudal fin. Later another Neon also had such a kink, but the other symptoms were not yet present. Furthermore the animals ate. Swam obediently in the shoal.

Fungal filaments were not noticed. However, on one neon the bump became larger and looked a bit bluish.

Ancistrus sp. albino with strong bacterial infection. On the first picture you can see him healthy, on the second picture he seems to have blisters and to bleed internally. The bubbles are possibly. cysts filled with fluid due to the infection.

bacterial infections in fish and ornamental fish all info and details

– promotes the health of. – strengthens the immune system – is not toxic to fish.

Photos: D. Hagedorn

Blue orfe with strong bacterial infection. The animal was found dead in a large swimming pond with a bloodshot spot in the front abdomen area. After ca. after one hour more abdominal areas were reddened. The initial red spot was also really bleeding, as well as bleeding in the anus area. This condition is shown in the left picture. The gills in the right picture seemed to be healthy.

Photos: Iris Kuspert

Veiltail goldfish with bacterial infection that had severe difficulty swimming. This is what u.a. the red spot on the body. The amption is supported by the thick belly and the protruding scales. This is usually caused by fluid accumulation in the body. Since many fish, despite thick bellies and scales that protrude further, swim in a normal position, it is reasonable to suspect that in this case the swim bladder is also affected. The fish was mostly lying on its back. Breathing very fast.

Whether you call it dropsy, swim bladder inflammation or bacterial infection is actually secondary. This could only be determined by cutting open, looking at the affected organs and determining the exact pathogen by means of a bacterial culture. Treatment trials with Baktopur. ESHa 2000 had no success. Possibly. you can try to support the fluid release of the cells by adding salt to the water, as described under abdominal dropsy. In general, however, it is very unlikely to be able to save fish that are so severely affected.

Photo: Stefan Schmid

Spotted barb with bacterial infection, recognizable by the very strongly reddened fins.

Photos: Ulrich Ruffer

Blue gourami with bacterial infection. In gourami with such symptoms there is suspicion of EUS.

Photos: Christina (Forum)

Red neon with bacteria colony.

Photos: coy (Forum)

Otocinclus with bacterial infection. In the affected aquarium also several Guppies had red spots on the head side and cracks in the tail fins.

Photos: Daniel Schutz

Yellow phantom tetra with bacterial infection. First a black spot appeared on the tail fin, which could be seen from both sides. A few days later a second spot became visible near the pectoral fin. Both spots now looked dark red. The fish swam slightly slanted. Gasping for air. A few days later the tetra died.

Koi with a severe bacterial infection, which can hardly be cured with over-the-counter remedies. Only a veterinarian can say whether this is due to spring anemia of carp (SVC), which does not only occur in spring.

Brief information

Bacterial infections in fish and ornamental fish all info and details

Bacterial infections in fish and ornamental fish all info and details

Main symptom: Red spots on body or fins
Causes: Bacteria multiplying rapidly, often due to poor water hygiene, stressed fish or with simultaneous parasite infestation
Curability: Curable if diagnosed in time. Hardly curable in case of heavy infestation. Both in the water and on the surfaces of the fish outside. In the body live many bacteria of different species. Additional bacteria get into the digestive organs of the fish through the food. Fish are thus even more at risk from bacteria than land-dwellers. But not all bacteria cause disease. Not all diseases caused by bacteria are fatal.

Normally there are no diseases if the fish is kept in good conditions. Due to the mucus formation of the fish, the bacteria cannot adhere to the fish skin, but they are in a thin film of mucus above the skin surface. The mucus has antibacterial components, some of which are effective against very specific types of bacteria, and some of which are effective against bacteria in general. In addition, the entire microflora of the mucus probably prevents the penetration of additional pathogens.

rank fights, catch and transport damages, sudden temperature changes, parasites etc. can cause the smallest, invisible damages to this mucus protection. These damages provide ideal conditions for the existing bacteria to multiply explosively.

Presumably, such damages are the reason for many of the repeatedly reported sudden mass mortalities, in which entire fish stocks die within a short period of time.

Also, the death of certain species of fish that sometimes occurs when new fish are purchased is certainly often not due to bacteria that are completely unknown to the immune system of the old or the new fish. The cause is rather that the bacteria, which have been living with the respective fish for a long time, suddenly find conditions in which they can spread rapidly.

Even under the best of conditions, the introduction of new fish can be stressful for the old tank inhabitants as well as for the new additions. Already the establishment of the new hierarchy, z. B. during feeding, can lead to the smallest skin damage. It depends on the individual case whether the existing fish or the new additions fall ill first. This depends on how healthy and strong the respective fish are and how strongly they are attacked by bacteria. Mycobacteria are particularly widespread, waiting in practically every aquarium for opportunities to spread.

There are also some strains of certain types of bacteria, z. B. Aeromonas, more deadly than other strains. If the affected fish have become immune to such a strain over time, it may be difficult to socialize these fish with other fish. Among fish without immunity to these strains, high losses can occur.

How such particularly lethal strains develop is not clear. Apparently the bacteria are under a special selection prere when they are attacked by the immune system of an infected fish. This can cause them to mutate into particularly deadly forms. If such strains are returned to a normal aquarium or cultured in Petri dishes, they lose their special danger in subsequent generations. However, this also means that once infected and seemingly cured fish may be carrying particularly deadly bacteria. Treatment does not usually kill all bacteria. The so-called antibacterial agents usually only delay the division of the bacteria. The cure of a bacterial disease must normally be achieved by the immune system of the affected fish, by achieving a balance between the immune system and the pathogens.

Bacterial infections are caused by various pathogens. In addition, viruses, parasites and poor living conditions can cause similar symptoms. The final and reliable diagnosis of a bacterial cause therefore requires a great deal of experience, the establishment of bacterial cultures and microscopic examinations. Bacterial diseases often lead to increased parasite infestation and vice versa. In case of symptoms of bacterial diseases, affected fish should therefore always be examined for parasites.

Bacterial pathogens are constantly present in the aquarium. In good husbandry conditions, the fish usually cope with the pathogens themselves and no acute illness occurs. Only when the balance between the pathogens and the immune system of the fish shifts in favor of the pathogens, acute disease occurs.

Possible causes for a shift in the balance can be:

– transport stress – wrong and one-sided nutrition – too high stocking density – unsuitable husbandry conditions (e.g., in the aquarium). B. ph-value, water hardness, lack of water hygiene) – unsuitable socialization – unsuitable diet – skin irritations (z. B. bite wounds, catch and transport damage, chemical water additives, improperly used remedies, sudden temperature changes, parasites) – sudden multiplication of pathogens (z. B. new fish, diseases)

Good husbandry conditions can reliably prevent the outbreak of bacterial diseases. Diseases in the early stages can often be successfully controlled by creating optimal conditions.

After injuries, fish are particularly susceptible to bacterial diseases in the affected areas.

Internal bacterial infections can result in fluid-filled cysts. These cysts may remain invisible from the outside, but may pinch nerve pathways responsible for body color, causing entire body parts to turn black. If the head is affected, the symptoms are similar to the symptoms of a thyroid tumor. Possibly such cysts are also signs of an infestation with sporozoa.

Infections with the bacterium Nocardia asteroides are also called false neon disease. These bacteria infect different fish species. Symptoms are similar to those of other bacterial infections, i.e. z.

Like this post? Please share to your friends:
Leave a Reply

;-) :| :x :twisted: :smile: :shock: :sad: :roll: :razz: :oops: :o :mrgreen: :lol: :idea: :grin: :evil: :cry: :cool: :arrow: :???: :?: :!: