Hydrothol is VERY effective on Sago but it is toxic to fish. I treated a lake earlier in the spring and had great results. It is pretty late to be treating in this manner and your growth will require more product. I agree with The Pond Frog that Fluridione may be a better choice to avoid fish toxicity. Even if you wait until next year and go with Hydrothol, they will need a safe haven to get away from the chemical. Your pond may not be big enough for them to find that spot.

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