Is there a parasite that can cause these wounds?

[Fishfinder1973]

I posted a photo of the pinhole that is in my rainbow sharks dorsal fin a couple of weeks ago which has now got slightly bigger,but he has a much worse wound just behind his anal fin.The wound is almost a perfect half moon shape,but I haven’t a clue how it happened.He also has a white mark on his flank,a couple in fact.The bad wound doesn’t seem to be healing and it’s red raw flesh.Could there be something sinister going on that could develop from a wound.Im wondering if it’s worth trying to save him as the wound looks like it’s eating away at his rear end,and i would feel terrible if he lost his whole tail.I haven’t a clue how this came about as he was fine.I also have an albino rainbow shark and that’s fine.Are there any parasites that can be directly related to rainbow sharks?
All replies much appreciated thanks.

 

[Rocky998]

That looks like a bite, but you said it started smaller making me think it could be fin rot that turned into body rot... What is the tank size? What are your tank params? What else is in the aquarium? And how long has your tank been running?

 

[Fishfinder1973]

That looks like a bite, but you said it started smaller making me think it could be fin rot that turned into body rot... What is the tank size? What are your tank params? What else is in the aquarium? And how long has your tank been running?

Thanks for the reply Rocky.
The tank is a 109g.
Params are ok,ph 6,0 ammonia,0 nitrite,15-20 nitrates and been running for 15 months.
As far as other occupants go,I don’t think there’s anything in the tank that could inflict such an injury.
It’s the pinhole in his dorsal that was smaller a couple of weeks ago.I thought it odd that it was a perfectly round pinhole,though This could be an entirely different issue.There are two white marks on him too,hard to describe.I thought he had maybe lost a couple of scales.Again I can’t see the link between them and that horrible wound.
It’s like he has caught himself on a piece of decor and took a chunk out of himself which now seems to be eating into him.He has been hiding under the wood,but hasn’t lost weight,so he is eating during blackout hours.
Hopefully he pulls through,because all I can do is keep the water fresh and clean.
Just to confirm, only fish bigger than him is the yo-yo loach,and the albino shark is the same size.The rest are small barbs and corys.

 

[Colin_T]

The other shark or yoyo loaches might have bitten it. It looks infected. You can try salt but if there's no improvement after a few days you will need a broad spectrum medication to treat fungus and bacteria.

The hole in the dorsal fin could be a bacterial infection. Guppies have been showing up with pin holes in their fins that gradually get bigger and eventually kill the fish. People have tried anti-biotics but it doesn't seem to respond. So it might be drug resistant bacteria coming form the fish farms.

But try salt and see if it helps.

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Before you add salt, do the following.

Wipe the inside of the glass down with a clean fish sponge.

Do a 75% water change and gravel clean the substrate.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. Wash the filter materials/ media in a bucket of tank water and re-use them. Tip the bucket of dirty water on the garden/ lawn.

Increase surface turbulence/ aeration when using salt or medications because they reduce the dissolved oxygen in the water.

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SALT
You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria, fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

 

[Rocky998]

If this is a new disease... Imma nick name it, DD, or Decay Disease.