saprolegnia fungus - treating tadpoles

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Figured I would share my experiences with a recent bout of saprolegnia on a group of Lorenzo tadpoles in a communal grow out. The short story is a tadpole died in a 2.5 G community grow out and I didn't notice. I found it decaying so I removed it, but then I noticed a second tadpole had strange growths on it. Here are images of the second tad that developed the problem:

Overall not a good sign. I immediately pulled the tadpole and checked on the remaining third tadpole that was farther along and it appeared fine [at the time]:

Here's the pulled second tadpole:

After googling around a bit I settled on a saprolegnia infection. I'm not sure of the cause of the original infection which I suspect took the first tad, but from what I have read, it was likely some kind of immunosuppression possibly due to stress. The problem *I think* I was encountering with the second tadpole may be the presence of elevated zoospores in the grow out following the death of the first tadpole. I only had Methylene Blue available that night, so I treated with MB in a cup, and a bit of salt in the original grow out to target any zoospores remaining in the grow out.

Unfortunately the second tadpole was too far gone, and it was dead by morning. I rechecked the remaining third tad that morning and it too was infected. I didn't get a photo of the fungus developing on the third tadpole, but referring back to the original image, I can now see the source:

So that little dot ended up being a full saprolegnia the next morning. I did some reading on treatments and picked up Malachite green (sometimes it goes by Victoria green in pet stores) that day. I treated the grow out tank itself with the prescribed amount of MG that evening. By the next morning, there was no visible sign of the fungus.

All this occurred two weeks prior to this post. The third tadpole has since morphed out and is outwardly healthy. Here it is in the grow out earlier this week:

Here was the article I found helpful on treating saprolegnia:

Hopefully this helps someone else if they ever run into this. It developed very quickly. I keep MB around for treating eggs, but I'll have Malachite green around now in case this happens again. It's probably uncommon for folks using cups, but I use these communal grow outs, so this may be one of the downsides to that rearing method.

I'm also wondering if MG could be helpful in treating eggs for fungus. It was impressive how quickly it worked in this case.
Jim from Austin |
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Indian almond leaves. Tannins should be used

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