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Emergency help - severe finrot in small ranchu


22 Apr 2022
Have been given a ranchu from a friend who did not know how to look after it and the poor thing is SERIOUSLY ill with fin rot to the point where it barely has any tail left at all.

It was previously being kept in a 35l cube which as far as I can tell was uncycled; it was dirty and as far as I could see had little to no cycle established (ammonia burns before fish arrived which I got under control with WC) and the finrot was progressing rapidly despite daily 50% water changes.

I've now moved it into a 60l temporary Ciano tank with a U2 fluval filter I removed from my cycled 200l fluval. The plan is for the ranchu to join my other goldfish in the 200 when its healthy. I've only just moved the ranchu and filter into the ciano so haven't been able to establish how the cycle in there looks yet as the filter I've removed from my main tank was only in there brielfly and so I'm not 100% how established the bacteria colonies are in it but I'm planning on testing water tonight when the ranchu has been in there 24hrs to establish some baseline parameters.

I'm struggling to keep the finrot at bay and it actually seems to have gotten a lot worse; the fish barely has any tail left and the rot is effecting its other fins as well.

How can I treat this? I don't have a particular hospital tank (The ciano was supposed to be that but the ranchu will need to live in this until it is bigger after recovery as it's a lot smaller than the fish I have in the 200.) I also don't have any other filter media I can spare for a makeshift hospital tank as I've used it in this new tank, and I have no idea how I should use medications as I have never had to before.

I have Myaxin finrot treatment, Esha 2000 and aquarium salt to hand after seeing all of these treatments recommended but I am seeing so much conflicting advice that I don't know what to do or which is the right course of treatment.

I'm also using Seachem Prime as a water conditioner and conscious of the fact that it can't be used with some medications such as Esha. How can I medicate this fish while also performing water changes, and what is the best course of action to treat the finrot for this poor fish?

Thank you

Simon Cole

25 Dec 2018
EHSA 2000 - I know the old list of ingredients but don't have any lying around to check: ethacridine lactate, proflavine, copper, methyl orange. I seem to remember that it had quinine?
Myxazin - Malachite green, formaldehyde, acriflavine.

If the tail is fin is missing, I would not worry because they usually grow back.
All you need is a large tub or a bucket and an air stone.
I usually keep a few buckets of treated water lying around for a few days so that any water conditioner has less of an effect upon the treatment. You can also chuck a bit of activated carbon into these buckets, but don't add this to the treatment tank.

I'm not adverse to either of the treatments that you have. I have used them in the past, but I haven't used them recently. EHSA 2000 is what they used at my local fish shop. Myxazin is a little bit less favoured due to it's formaldehyde content because this makes it more toxic in soft water. For other people, the copper concentration of EHSA 2000 isn't quite right due to the presence sensitive species. Both are suitable treatments in my opinion. There are a few on the market that I would never touch, but either of these treatments could be ideal. But note that if you use then in your main aquarium then they can stain silicone.

Aquarium salt is used to improve osmoregulatory balance, and in fish with lesions this is rather helpful. It has been used to remediate nitrite poisoning, it has good properties against external parasites, and there is limited evidence that it has antimicrobial properties that can be used to treat certain fin infections. It is something I will use after I have completed the initial treatment to promote healing of fin damage. Usually people increase the concentration gradually or just opt for isostatic equilibrium, which is what I do. It is more of a secondary treatment, and I would revert to it after treatment if your fish was not eating for instance.

Saying all that... what do I tend to do these days? Not that I advise this, but for most fish I start with a 20 minute 2 ppm potassium permanganate bath, using a net, an air stone and a bowl in the sink. Then I transfer the fish into a clean tub of untreated water and change the water every day, perhaps giving the fish more baths if the infection is spreading. I like to completely change the water and I don't like the idea of fish sitting in water full of chemicals, so I don't really use your treatments. I will use aquarium salt in the treatment tub occasionally when I am focussing on healing or if there is a particular need. I don't see the point of treating aquariums in order to treat fish, and I don't heal fish in aquariums because I prefer a far cleaner environment for them. I wouldn't really advise using potassium permanganate unless you have a good set of scientific scales and some experience working with chemicals. I know it gets a bad wrap, but it is what works for me and I like having control over the concentration and application. It is what I will use to sterilise nets, tanks and equipment between water changes, and generally I try to keep the treatment tank as sterile as possible, being very careful to only feed fish one flake at a time, and immediately siphoning out any contaminant. I will use a lid or cling film to stop dust, hair or debris from entering the treatment tank. Once the fish is externally sterilised and the tank is sterilised, it becomes very easy to get full recovery. I may switch back to a standard treatment one day and if I did, the ones that you have would be my top choice.

White marks on the edge of the fins is regrowth. This is what you want to achieve. It can look a bit like fungus, but most treatments will knock that off very quickly. Then I just concentrate on a healthy diet.