Guppy fin turning black. Help!

[rockvillemmf]

I've been keeping kohaku guppies for about a year. Of the four that I have, one of them has developed a black spot on it's tail fin. I noticed this about a week ago, and need to know how to treat it, and if it should be isolated. I've looked on the internet for info but can't find anything that looks similar. The only thing I've found is about guppy fins turning black from stress, but as you can see in the picture, the top part of the fin that has turned black has disappeared.

Any help or advice is appreciated.

 

[Rocky998]

Well if those spots can appear due to stress, it very could well be stress.
She could be having a case of fin rot.

 

[AdoraBelle Dearheart]

I really don't like the look of it... it's not just the fin, it's the base of the tail where it meets the body, and it looks like nasty reddish bumps -almost like a cancer or tumour. But, I'm not a disease/illness expert, I just really don't like the look of it. Wish our disease person was around.

 

[rockvillemmf]

Well if those spots can appear due to stress, it very could well be stress.
She could be having a case of fin rot.

Thank you for your comments. All the examples of fins changing to black on guppies did not appear to have the fin actually deteriorating or getting eaten away as in this case. Based on your comment, and the one that followed yours, I'm beginning to think it may be fin rot, or maybe even something more serious.

 

[rockvillemmf]

I really don't like the look of it... it's not just the fin, it's the base of the tail where it meets the body, and it looks like nasty reddish bumps -almost like a cancer or tumour. But, I'm not a disease/illness expert, I just really don't like the look of it. Wish our disease person was around.

Thanks for your comments. Starting tomorrow, I'm going to isolate this guppy, and treat it for fin rot seeing as that's the only possible remedy I can think of for now. As far as I can tell, none of the other guppies or striped danios (4 of them) in the same tank have anything like it. But, as you say, I wouldn't rule out the possibility that it's something worse.

 

[AdoraBelle Dearheart]

Thanks for your comments. Starting tomorrow, I'm going to isolate this guppy, and treat it for fin rot seeing as that's the only possible remedy I can think of for now. As far as I can tell, none of the other guppies or stripped danios (4 of them) in the same tank have anything like it. But, as you say, I wouldn't rule out the possibility that it's something worse.

I'm sorry I can't be of more help! It would be interesting if you could take progress photos every few days/weekly, and see how it either develops or clears up. I wish I could offer a more optimistic thought- and it's a really pretty guppy- but I really don't like the look of that...

 

[AdoraBelle Dearheart]

Keeping fingers and fins crossed!

 

[rockvillemmf]

I'm sorry I can't be of more help! It would be interesting if you could take progress photos every few days/weekly, and see how it either develops or clears up. I wish I could offer a more optimistic thought- and it's a really pretty guppy- but I really don't like the look of that...

Just finished isolating the guppy into a 5 gallon pail with a sponge filter. I am treating with mardel maracyn, and will do this for 5 days as recommended by Fritz Aquatics. I will post photos every few days. Fingers crossed.

Thanks again.

 

[GaryE]

A black spot radiating out from the tail base can very often be Melanoma, unfortunately. Livebearers get the same skin cancers humans do.

 

[rockvillemmf]

A black spot radiating out from the tail base can very often be Melanoma, unfortunately. Livebearers get the same skin cancers humans do.

Yeah, that seems like a distinct possibility. Since there isn't much that can be done if it is cancerous, I'm just doing what I can hoping that it is fin rot. I will provide updates. Thanks for your comment.

 

[GaryE]

I don't like making that comment, but I have seen it before with swordtails, often. If the black is entirely unreflective, watch out. The bubbling on the top of the caudal never appears with fin rot. The outer rays of the fin will die off if a tumour is cutting off blood supply.
The treatment won't harm her, but is extra stress.
There is a black spot disease that tends to hit outdoor fish and is a parasite. It's harmless and untreatable - it just sits there waiting for its true host, a bird, to eat the fish and be infected. It forms on the body, not the caudal peduncle.

 

[emeraldking]

To me it also looks like Melanoma. If it starts to get bubbly on that spot, it's definitely cancer.

 

[AdoraBelle Dearheart]

To me it also looks like Melanoma. If it starts to get bubbly on that spot, it's definitely cancer.

There are definitely bubbles, you can see them on both sides Not easy to see, but it's what made me think cancer as well.

 

[rockvillemmf]

There are definitely bubbles, you can see them on both sides Not easy to see, but it's what made me think cancer as well.

Hoping for the best, expecting the worst.

 

[emeraldking]

Hoping for the best, expecting the worst.

Fingers crossed...