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Hydra problems

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Hello. I had a tank full of females, then I got two berried ladies in an order from The Shrimp farm, and both their eggs hatched maybe a weekish ago, the babies are tiny but they were everywhere. I  had started examining my tank with a magnifying glass a few days before they were born, and only saw an odd nematode and a harmless (not planaria) flatworm or two. Then the morning after I saw all the babies (Babies ALL over the glass one night) I saw a hydra. And another. I'd never seen one in my tank before. I have to assume I had picked them up somewhere but their population blew up when the babies were born because the hydra spread fast and I seem to have lost a ton of babies. First I sucked any I could find out with my coral feeder pipette (I don't keep corals, it's just super useful), then I dosed the whole tank with h2o2, that seemed to perk up the shrimp the next day, but didn't affect the hydra unless I hit them with it directly.  Then I finally got my fenbendazole in. I took out my snail, and dosed 0.1mg/10gallons like everyone said, next morning the hydra were still there, unperturbed. So I gave them another half dose that same AM. Then that night (yesterday) I gave them another half dose. Still have hydra doing just fine. I marked where a couple of them are so I can see if they're actually dying, and am removing the rest. I know they're on my plants too, but I can't see all of them, I got what I could.


I don't know what else to do, how can they be immune to fenbendazole?


Just FYI my shrimp seem just fine, very active and eating well.

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I believe your dosages are off. When I had Hydra, I dosed 1ml/10 gallons NOT .1ml/10 gallons.


Make sure it is dissolved (as best you can) before administering. I found it far easier using pre-dissolved liquid Panacur from a vet (here in Canada).







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Everything I've read said to dissolve 1 gram of the 222mg/g powder in x amount of water and dose 0.1g (100mg) (sorry, that was a typo before, I wrote 0.1mg/10gallons) of it per 10 gallons. I have a 2.5 gallon tank that technically holds 3.4 gallons max based on dimensions, and I've worked out that it's got 2.1 gallons of water in it if I subtract the air space, substrate (used a substrate volume calculator for that) and plants/filter. I couldn't for the life of me find anyone who could clarify if it's 0.1g of fenbendazole or of the powdered meds itself, and half the people giving dosing instructions didn't even mention how big their tanks are so it's not helpful. I did find this: 


and this: 


In the first, hambone has a three gallon, and divided a 1g pack (222mg of med) into ten piles, then divided one pile into three, and used one of those piles, and that worked. Not knowing the volume of water in her 3-gallon, that still works out to around 0.033~g (33.3~mg) powder, or 7.4mg fenbendazole, for their 3 gallon.


in the second example, he has a 10-gallon. He puts the one gram (222mg fenben) of powder into 220ml of water, so each ml is 0.004545~g (4.545~mg) powder or 1mg fenbendazole. He dosed 20ml (20mg fenben) for his 10g.


I dosed 0.025g (25mg) powder or 5.5mg fenben for my first dose, which I thought was a bit high given both examples, and then half that at the two subsequent doses. No water changes. That's 0.05g (50mg powder)/11mg fenben in two days for 2 gallons of water. I thought that was a lot, so I stopped there.






The liquid looks to be 100mg fenben/ml, so basically I need to use double what I used to equal the liquid dosing you use? Since I haven't changed my water or added carbon yet, would it be sufficient to just add another 10mg of fenben or should I dose the whole 20mg?

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