Hi all

Please have a look at the below pics. Would you say this caused by bacteria or fungus or could this just be a normal injury? This fish is swimming around normally and eating like a maniac. It was in quarantine with 3 other new arrivals and they were very rough at feeding times. When they came out of quarantine I noticed that the fin was split and then 1 week later I noticed what you see in the below pics. The water is yellow because I added Acriflavine in the bowl and yellow bits floating is because of salt also added to the bowl to disinfect the affected area.

Thats finrot caused by bacteria in unhealthy water / living conditions. Its usually also the first sign that something else like ulcers can break out. You may observe some fungus on the wounds but the bacteria is the first culprit, fungus will join the fun after the bacteria has done some damage.

1. Check your total alkalinity (TA) please. Acid water and PH swings can cause stress and casue finrot aswell.
2. I would do a 20-30% water change on the pond and clean all the filters as the problem is in the pond. And make sure the pond floor is clean. Do the normal 10-20% water changes weekly.
3. I will then PP dip the affected koi.
4. Then push the salt levels in the pond upTO 0.3%.
5. I would then follow up in one week by cleaning the affected areas with a strong mixture of Vrikon S applied with cotton wool.
6. Then dry the fins and do a topical treatment on the red infected areas and on the white milky areas, i would use malchalite green crystals and then seal it with frairs balsam and repeat it then weekly until you see an improvement.
7. If you want you can even do a 2 or 3g / 1000liter virkon S treatment to bring the bacteria count in the pond down. (Remember this can affect your bacteria in the filters. A normal dos is 5g/1000liter thats why i suggested 2 or 3g)

The key here is to keep the pond and conditions healthy. If it was me then i would move the koi to qt where i could control the water beter and where its easier to keep an eye on the koi and its progress.

fishdoc.com wrote:

With very few exceptions, virtually all cases are precipitated by stress, fear or poor environmental conditions. Indeed, fin rot is often one of the first signs that a fish disease problem exists and all cases should be investigated to determine the underlying cause. When I have fish in for hospitalization, occasionally some sensitive fish will start to develop fin rot as a consequence of their strange new surroundings and being handled – even though they are being kept in optimum conditions. It is usually self-resolving as they settle in, but does demonstrate just how sensitive fish can be to stress and how fin erosion is often a sign that all is not well.

fishdoc.com wrote:

Treatment

At the expense of being repetitive, stress is the major cause of fin rot. This could be due to a fish disease such as parasites, or overcrowding, low oxygen levels, bullying, poor water quality etc. The most important first step is to resolve any stressors. If caught early, this may be sufficient.

In more advanced cases it may be necessary to trim the affected fin and remove the necrotic tissue. This has to be done when the fish is sedated. It is important to use sterile scissors and treat the clean edge with an antiseptic such as povodine-iodine. This procedure does carry with it a risk of secondary infection and it is important that the fish is returned to optimum conditions and its progress closely monitored for the next week or so.

If the fin rot has advanced the full length of the fin and is threatening the body, this procedure would need to be accompanied by a course of suitable antibiotics.

Does the tissue grow back? In minor cases where only the fin tissue is affected it probably will, but in more advanced cases, particularly if the fin rays (bones) are affected, the chances of re-growth are slim

from wikipedia wrote:

Fin rot starts at the edge of the fins, and destroys more and more tissue until it reaches the fin base. If it does reach the fin base, the fish will never be able to regenerate the lost tissue. At this point, the disease may attack the fish's body directly.

from wikipedia wrote:

In aquaria common treatments are to do a major water change, add aquarium salt if the species can tolerate it, and make sure that a healthy balanced diet with a lot of vitamins is provided. There are many commercial medications available for treatment.

Hi Chris

If it is only this fish, I would not worry too much about a 30% water change at this stage or treatment of the whole pond. This one individual fish probably got infected because of the stress of the new environment and QT procedure.

I would do the Malachite green paste treatment on the infected area and cover with Frairs Balsam to seal as Wayne suggested and put it back into the QT facility it came from. Repeat the topical treatment weekly until you see an improvement. It is good to have a hairdryer handy to dry the medicated area before releasing it back into the water. (set on cold)

Bring the salt level to 4kg/1000 in your QT facility and proceed with the Acraflavine to bring the bacterial count down. PP or Virkon as suggested will also work, but you already started with Acraflavine, it is not heavy on your filters, so stick to it. (It is not good to mix various medications)

Should any other fish in the pond show signs of infection, you will have to treat the whole pond. In the circumstances, monitor the rest of the fish carefully.

Hi Wayne
ek glo nie hierdie is fin rot, dit lyk vir my die fin het gebreek miskien kan Chris se of hy dalk n merkie gesien het voor die tyd. Gewoontlik so klein rooi kol op die fin been.
Sou maar die dam dophou finrot sal vinnig versprei as daar n probleem is.
Admin gee goeie raad later sal Chris maar die fin n bietjie moet trim.

I noticed a split when removing the fish from QT (split is clearly visible in the second pic under the broken off piece). After about 4 days in the main pond I noticed the top part had broken off. Non of the other fish show any strange or similar symptoms.

When I mentioned originally that they were rough at feeding times, I mean ROUGH!! For the first week in QT they didn't eat but then they started eating. They literally nearly jumped out of the water to eat and bumped each other like crazy.

In my opinion I think that it's an injury due to this feeding frenzy which ended up in the top piece of the tail breaking off. I've now put this fish in another QT with one of my smaller fish. I've only treated the water in this QT with salt for now and will observe what happens from here. The salt should also disinfect the area fairly well.

Won't use any anti-bacterial meds unless I'm sure there's bacteria present ie. if it gets worse. Will do a topical treatment by disinfecting with Hydrogen Peroxide, then applying Melachite Green and sealing with Friars Balsam. Will then add Acriflavine to the water.