Loose stools and treatment-resistant fin rot

What it says on the tin.

Noticed this neon starting to poop earlier. Maybe 30-45 min ago. Just looked again, and now this monstrosity is hanging from her rear end. She's acting completely normally, swimming around just fine. She ate just fine earlier too. I guess I've noticed her hogging the food a bit at mealtimes the past few days.

The only thing different about the tank recently is that 2 days ago I started a round of meds for some stubborn fin rot. Kanamycin and nitrofurazone. I just added the second dose of kanamycin earlier today. Other than that, all parameters are normal (no ammonia or nitrites, low nitrates).

Really hoping she's just having the crap of a lifetime and that these aren't her intestines... There are bits of whatever this is coming off as she swims. I feel like if it were guts, they'd hold together better. It's just, well, this seems excessive.

Certain antibiotics can cause diarrhea in mammals. Maybe it’s the same for fish.

Okay, well, it all just fell off and she's still acting completely normally, so I can only assume she feels a heck of a lot better now

gwand said:

Certain antibiotics can cause diarrhea in mammals. Maybe it’s the same for fish.

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There might be something to this, yeah. I couldn't find any solid list of kanamycin side effects on fish, but at least one person on a different forum mentioned diarrhea, so it's possible.

@gwand beat me to it! But my guess was also going to be that it's the antibiotics, since they themselves often cause diarrhea in humans and other mammals, and given that they work by eliminating bacteria without targeting "good" vs "bad, I don't want this" bacteria, it's a common and understandable side effect!

It doesn't look anything like a prolapse, or a wound on the fish, which was my first concern when I read the title and saw it was you posting.

I also agree to take some deep breaths, you're an excellent fish keeper!

This is your original neon rescue girl though, isn't it? I'm sure I can also recognise her looks compared to your newer, younger school you got to keep her company, so I can also completely understand why you'd worry and want second opinions when you saw the loose stools!

ETA: Will also keep fingers crossed that the antibiotics work to wipe out the stubborn fin rot. Don't panic about loose stools, but just keep a slight eye on their general appetite and if the loose stools continue/worsen/any other concerning symptoms.

But!! I don't say that to cause you any additional worry. My experiences with diarrhea/vomiting and side effects to antibiotics comes from human patients, or from pet mammals and most especially avians like my pet birds, where they're far more at risk from a reduced appetite and/or loose stools, since they don't have the benefits of being cold blooded like fish are, and can lose body condition and water resources far more rapidly.

So my bird-keeper/dog guardian brain wants to warn you to keep an eye, just in case, and update with any changes.

Fish hobbyist brain knows fish would be fine for weeks even if an upset stomach reduced their appetite, and that the antibiotics course will have been designed around aquatic life too. Just my disclaimers added in there!

After I use antibiotics in a tank I restore gut flora with Dr. Tim’s Eco Balance. It’s like a human taking probiotics after antibiotic therapy destroys good as well as bad bacteria.

Hello. Things that are out of the ordinary, should be a "red flag" that you're doing something that's not standard procedure or "outside the norm". You can't feed the fish too much and putting chemicals into the tank water other than the standard water treatment or a little standard aquarium salt is risky at best, because you can't predict how the fish will react. If you keep things simple, by changing out the tank water regularly and feeding a little every day or two, the chances of making a mistake are really pretty remote.

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AdoraBelle Dearheart said:

@gwand beat me to it! But my guess was also going to be that it's the antibiotics, since they themselves often cause diarrhea in humans and other mammals, and given that they work by eliminating bacteria without targeting "good" vs "bad, I don't want this" bacteria, it's a common and understandable side effect!

It doesn't look anything like a prolapse, or a wound on the fish, which was my first concern when I read the title and saw it was you posting.

I also agree to take some deep breaths, you're an excellent fish keeper!

This is your original neon rescue girl though, isn't it? I'm sure I can also recognise her looks compared to your newer, younger school you got to keep her company, so I can also completely understand why you'd worry and want second opinions when you saw the loose stools!

ETA: Will also keep fingers crossed that the antibiotics work to wipe out the stubborn fin rot. Don't panic about loose stools, but just keep a slight eye on their general appetite and if the loose stools continue/worsen/any other concerning symptoms.

But!! I don't say that to cause you any additional worry. My experiences with diarrhea/vomiting and side effects to antibiotics comes from human patients, or from pet mammals and most especially avians like my pet birds, where they're far more at risk from a reduced appetite and/or loose stools, since they don't have the benefits of being cold blooded like fish are, and can lose body condition and water resources far more rapidly.

So my bird-keeper/dog guardian brain wants to warn you to keep an eye, just in case, and update with any changes.

Fish hobbyist brain knows fish would be fine for weeks even if an upset stomach reduced their appetite, and that the antibiotics course will have been designed around aquatic life too. Just my disclaimers added in there!

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Yes, this is my rescue girl! She's still doing well today, although I did notice another big stool from her. She's acting and eating normally though, so I'm not too concerned. It's interesting, I haven't noticed any abnormal stools from anyone else, so it seems it's just her that's affected. Maybe because she's a bit older? Who knows.

I am really hoping I can get this fin rot figured out though... I'm starting to worry because I haven't seen any improvement at all so far. I feel bad for the poor little guy who has it. I guess I'll try a week or two of more frequent partial water changes once the course of meds is done and hope for the best.

AdoraBelle Dearheart said:

But my guess was also going to be that it's the antibiotics, since they themselves often cause diarrhea in humans and other mammals

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... Guess who also started a course of antibiotics on Monday, had a raging infection in my face that's making me miserable, and has an upset stomach from the antibiotics I know I do need? And last night was flickering between hot and cold, so know I'm feverish too.

So I'm feeling like your girl right now!

AdoraBelle Dearheart said:

This is your original neon rescue girl though, isn't it? I'm sure I can also recognise her looks compared to your newer, younger school you got to keep her company, so I can also completely understand why you'd worry and want second opinions when you saw the loose stools!

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Seisage said:

Yes, this is my rescue girl! She's still doing well today

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I knew it was her!

Seisage said:

although I did notice another big stool from her.
She's acting and eating normally though, so I'm not too concerned. It's interesting, I haven't noticed any abnormal stools from anyone else, so it seems it's just her that's affected. Maybe because she's a bit older? Who knows.

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Could be lots of factors. Remember that even in humans, the same drug can have different effects on different people for many different reasons.

Your rescue girl is older yes, and that might be the cause - but she was also the last survivor from an office tank, if I remember rightly? Then you got the newer younger school a long time later as one large group that would have been freshly imported. Their gut microbiomes will be different based on lifestyle factors for one thing, and that could also account for the difference, given she's been on commercial foods for a lot longer, we don't know what the person you got her from fed that tank, different water conditions for her and her original group when shipped/in stores/in the office tank vs your home tank... too many variables to know for sure!

But even humans living in the same household consuming the same diet will have variation in gut bacteria and responses to medications like antibiotics, so I don't find it surprising or anything to be alarmed about, especially while she's still actively swimming and eating.

The main worry with mammals and avians with having loose stools is losing fluids rapidly, and generally feeling unwell often means a loss of appetite too, and especially birds and small furries with fast metabolisms can be in grave danger within 1-3 days. Given that she's swimming in and breathing her fluids, still eating and could last a long time even without food, those concerns are much less serious. But a fish that still has an appetite is always a good sign, right?

Seisage said:

I am really hoping I can get this fin rot figured out though... I'm starting to worry because I haven't seen any improvement at all so far. I feel bad for the poor little guy who has it. I guess I'll try a week or two of more frequent partial water changes once the course of meds is done and hope for the best.

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I'm not much help with fin rot I'm afraid, I'm sorry! Is it just the one that has it? Perhaps see how he's doing once the antibiotic courses are done? If you're able to take clear, ideally macro shots of the affected fins, you might see a noticeable difference if you compare before/after shots that you might not pick up on with the naked eye, especially since regrowth is usually so transparent or white tipped?

Crossing fingers for you and your fish though!

Do you have photos of the fin rot? Is it visibly reducing the size of the fins?

GaryE said:

Do you have photos of the fin rot? Is it visibly reducing the size of the fins?

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Yes, which is why I suspect rot instead of something simply growing on the fins.

This photo is from May 8, two months ago


These photos are from today — you can see the lower lobe of the caudal fin is noticeably smaller



It seems like it's been fairly slow to progress, but it has definitely gotten worse, and has not responded to treatment. So far I have tried salt at 1tbsp/5gal and then 2tbsp/5gal, daily 25% water changes for ~10 days, and food medicated with doxycycline (API Fin&Body Cure). The kanamycin and nitrofurazone combo was one I was saving as a "last resort", but I'm not sure it's even doing anything...

That's ugly, and unfamiliar. I can't legally get antibiotics here without a vet's script. Because of that, If it is one fish and you're feeling desperate, I would try betadine. Net the fish, and over a paper towel or something to absorb the stains, paint the wound while the fish is on a net. You have to work fast as the fish is out of water, but it can sometimes heal lone fish with infected wounds.

I haven't tried it on that. It sort of resembles Flavobacterium columnare, a gram negative infection. But that's on the eyeball test, from thousands of km away...

GaryE said:

That's ugly, and unfamiliar. I can't legally get antibiotics here without a vet's script. Because of that, If it is one fish and you're feeling desperate, I would try betadine. Net the fish, and over a paper towel or something to absorb the stains, paint the wound while the fish is on a net. You have to work fast as the fish is out of water, but it can sometimes heal lone fish with infected wounds.

I haven't tried it on that. It sort of resembles Flavobacterium columnare, a gram negative infection. But that's on the eyeball test, from thousands of km away...

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Yeah, this is why I've been so concerned. It looks mostly like fin rot, but fin rot is typically rather straightforward and simple to treat, and I'm sort of at wit's end trying to find something that works. I hear your F. columnare concerns. That's another reason I chose the kanamycin/nitrofurazone combo. I've heard from multiple sources that it's one of the few med combos that actually is effective against it.

I'll look into the betadine though, thank you. I wanted to stick to treatments that could go directly in the tank because trying to net this fish to move him was what caused the injury that led to the rot (did the typical first aid of keeping water clean, but it obviously didn't work out...), but if this is something that can only be treated by direct and specific intervention, then I'll have to give it another go.

Would the betadine be a one-time application, or multiple?

Betadine isn't commonly used for fish. It was suggested to me for an injury to a red eared slider turtle many years ago, and she recovered. I had read of iodine being used by 1930s aquarists, and I have tried it on a couple of infected wounds on fish with success. I keep it out of the eye and gill area, and use it on caudals, mainly.

What's off with your neon is he is alone in this. Usually Flavibacter starts showing up on other fish.

Is it a one off treatment? It may do nothing, it may work once, it may need several treatments. It's a suggestion I'd use in desperation to keep that pathogen from reaching the peduncle. Is it bacterial or fungal? I can't say, but it looks largely unaffected by a good antibiotic mix.

I'd even consider a fin snip and something topical.

Seisage said:

It seems like it's been fairly slow to progress, but it has definitely gotten worse, and has not responded to treatment. So far I have tried salt at 1tbsp/5gal and then 2tbsp/5gal, daily 25% water changes for ~10 days, and food medicated with doxycycline (API Fin&Body Cure). The kanamycin and nitrofurazone combo was one I was saving as a "last resort", but I'm not sure it's even doing anything...

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I would try one dose of Maracyn (erythromycin) and wait a week. Erythromycin cures tail rot too and primarily attacks gram-positive bacteria. Kanamycin attacks primarily gram-negative bacteria. I have used both antibiotics when one didn't work and then the other succeeded.

Seisage said:

I wanted to stick to treatments that could go directly in the tank because trying to net this fish to move him was what caused the injury that led to the rot (did the typical first aid of keeping water clean, but it obviously didn't work out...), but if this is something that can only be treated by direct and specific intervention, then I'll have to give it another go.

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There might not be anything useful to you in here, but I've found the different techniques helpful even though I'm generally adab hand with the net from toddlerhood in the shop, lol. And Aquarium Co Op's content can be hit or miss, depending, but he covers so many techniques with a net here, to cause the minimum amount of panic to the fish, that I don't think there any many people who couldn't find something in this video handy... worth a share just in case anything helps, and you have to net him - I especially like his tips for when you ease several fish into the net, then can select which to release from the net, and how, leaving just the one(s) you're after in the net.

Most of this for you will be teaching your grandma to suck eggs, but just in case you or anyone else finds it as useful I did