Help with unknown spots on guppy tail fin only

[deedeefish]

What could these flat white spots be? I have had the guppy quarantined for 2 weeks, he is acting complete normal, social and eating readily. I only QT him because the large spot was strange and he has a few tiny ones all on his tail fin. It’s more of an absence of color than anything fluffy, cyst like or granular. He is not rubbing on anything nor does he seem irritated in any way. To me they don’t look like fungus, lympho, ich or velvet, although I personally only ever treated ich and fin rot. I’ve treated with a full course of kanaplex and paraguard with no changes. He didn’t even seem phased by the meds. I also used some melafix for a few days.

 

[Jay Hemdal Verified Community Expert]

What could these flat white spots be? I have had the guppy quarantined for 2 weeks, he is acting complete normal, social and eating readily. I only QT him because the large spot was strange and he has a few tiny ones all on his tail fin. It’s more of an absence of color than anything fluffy, cyst like or granular. He is not rubbing on anything nor does he seem irritated in any way. To me they don’t look like fungus, lympho, ich or velvet, although I personally only ever treated ich and fin rot. I’ve treated with a full course of kanaplex and paraguard with no changes. He didn’t even seem phased by the meds. I also used some melafix for a few days.

Welcome to Reef2Reef!

How did these spots develop? Rapidly, or over time?

The iridescence of them is unlike any disease that I've ever seen, I'd hazard to guess that they are guanine - part of the fish's coloration that is somehow showing through more in one spot than another.

 

[deedeefish]

Thanks for the reply, the initial large spot was fairly rapid over a few days, and then took a week or two for the other smaller spots to show. They do catch the light as he swims and appear bright white, and they are getting slightly larger. I had also read about lysine for viral conditions and fish immunity and tried one dose of that. At this point I’m not sure if I should just put him back in the main tank.

 

[Jay Hemdal Verified Community Expert]

Thanks for the reply, the initial large spot was fairly rapid over a few days, and then took a week or two for the other smaller spots to show. They do catch the light as he swims and appear bright white, and they are getting slightly larger. I had also read about lysine for viral conditions and fish immunity and tried one dose of that. At this point I’m not sure if I should just put him back in the main tank.

So - going back 50 years or so, I dimly recalled that "gold tetras" in the pet trade are that color due to a disease that causes them to produce extra guanine. I looked it up and yes, it's a thing:

Wild Gold tetra are stunning, with the standard metallic-gold appearance in which their name comes from. The cause for this coloration, however, was found out to be a response to a type of trematode parasite, causing the fish to deposit guanin in their skin.

So - I don't know if guppies get the same issue, but maybe?

Jay

 

[deedeefish]

So - going back 50 years or so, I dimly recalled that "gold tetras" in the pet trade are that color due to a disease that causes them to produce extra guanine. I looked it up and yes, it's a thing:

Wild Gold tetra are stunning, with the standard metallic-gold appearance in which their name comes from. The cause for this coloration, however, was found out to be a response to a type of trematode parasite, causing the fish to deposit guanin in their skin.

So - I don't know if guppies get the same issue, but maybe?

Jay

 

[deedeefish]

Good info, I tried paraguard with no change. Is there a specific parasitic/protozoan med you’ve used that works better?

 

[Jay Hemdal Verified Community Expert]

Paraguard really doesn’t work against trematodes. I would consider dosing with Prazipro.