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Discussion Starter · #1 · (Edited)
Just posting this in case any others are looking for a resource on experiences with treating hydra with fenbendazole.

I noticed a rather large quarter inch sized hydra, with two small conjoined hydras hanging out in the corner of my tank. I freaked out because almost all my cherries and ghosts are currently berried. To pave a safe path for their development I went the route of drugs.

Day 1:
Based on an article I found on planetinverts I stuck to the .1 gram/10 gallon concentration for fenbendazole. The fendbendazole was sourced from a SafeGuard dog dewormer from Walmart. I took the 1 gram package containing 222 mg of fenbendazole and added the entire package to 10 ml of filtered water. I then took 3.6 ml (working concentration of .1 gram/ml) of that solution and injected it straight into my tank in the direction of the filter intake.

Almost instantaneously I saw a 1-2 inch pale white worm shoot up from the gravel and begin to crawl up and out of the water column. I figured the compound must be having an effect. The shrimp and fish showed no change in behavior.

Day 2:
I inspected the tank for dead shrimp, fish and hydras. Seeing that the hydra was still alive I decided to administer a second dose of the fenbendazole at .1 g/10gallon once again using the same procedure. This means, given 22.2 mg/ml, the amount of fenbendazole in the tank should be roughly 160 mg at the conclusion of the second dose.

This time after a few hours I noticed that the cherry shrimp, but not the fish or amanos, were acting sluggish. They moved very little, and were not picking at gravel/plants. I decided to back down the concentration by doing a 25% water change. At this point the concentration of the fenbendazole in the tank should be somewhere around 120 mg total. Immediately after the change the cherry shrimp began acting more normal but still less active than normal. At this point it has been several hours with 120 mg fenbendazole in the tank. Keep in mind all values are only rough calculations given that my canister filter adds volume to the 36 gallon amount but the rocks and gravel detract from that volume.

Day 3:
Last night I observed approximately 5 small ghost shrimp larvae clinging to the sides of the aquarium. Fenbendazole at the above concentrations is not lethal to them in the short term. There are no dead fish or shrimp in the tank and there is now a noticeable lack of worms floating in the water column or digging around in the algae. I'm not observing any hydras either.

Given that no long-term dosing has ever been documented I once again performed a 25% water change. At this point I'm pretty comfortable leaving the tank as is until tomorrow when I will introduce a bag of carbon to remove any residual fenbendazole. There doesn't seem to be any literature which describes the natural decay time of fenbendazole. Half-life, as I understand it, is in the context of being inside the human body which continuously removes non-self molecules. It could be entirely possible that the fenbdazole has broken down completely or isomerized into other compounds but I will add carbon just in case. Given the aforementioned difficulties in determining concentration all I can do is operate on assumptions and calculate that the concentration of fenbendazole in the tank is approximately 90 mg or 25 mg/10 gallon at this point.

Day 4:
Got busy and nothing was done to the tank. Everyone still happy. Ghost shrimp larvae are still clinging to the tank walls at night.


Day 5:
Single bag of carbon added. Thus far I have not seen any unwanted deaths. The tank is completely devoid of hydras and worms. Copepods are still shooting about the tank which is nice to see. I don't suspect that I'll update this again unless I see hydras return. Overall I wouldn't hesitate to use fenbendazole in my tank again and will definitely be bathing anything that enters my tank in it from now on.
 

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Sorry for necro but just want to add my experience to the thread.

Gonna keep it short and simple, read this thread and some others after I had issues with random shrimp death in my two 50L shrimp tanks (only shrimp). Both tanks had shrimp die at random and could not figure it out. Water parameters was perfect, tanks overfiltered etc.
Was sitting down watching some 1mm shrimplets scavenge for food when I saw one just shoot at away at random and then falling to the side and die after a little while. Took a closer look at the gravel and saw those [censored][censored][censored][censored]ty little things called hydra. Never saw one before and thought they were bigger so I had missed them, when I knew what to look for I saw them friggin everywhere.

Decided to go the Fenbendazole way but since it has such low solubility in water I decided to try something called Axilur, an oral suspension for dogs and cats.
The bottle is 50ml and has a total of 5 grams of fenbendazol suspended. I decided to try a 1ppm dose (0,5ml).
Added it to both the 50L tanks before lights out and watched. The tank got pretty cloudy but I could still see the hydras in the front of the tank. Almost instantly they reacted to the suspension and retracted their small tentacles not to come out again.
Day 2 the tank had cleared up again and I could see the hydra, they were as far as I could tell still alive but not with their tentacles (arms, whatever)out. Dosed another 0.5ml before lights out.
Day 3 I could no longer see any hydra in the front but still see some on the back glass (big colony there) they were only small stumps now though.
Have not added anything since and it is now day 5 and I can no longer find any hydra in the tank. Will do one last dose tonight just to be safe and then call it a success.

Have not had any more shrimp deaths during this period, there is 1-2mm shrimplets still roaming around in the tank, small snails still alive and small copeopods.

:)
 

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Was sitting down watching some 1mm shrimplets scavenge for food when I saw one just shoot at away at random and then falling to the side and die after a little while.
I saw the same thing happen a few weeks ago. Saw a fry jump, then fall to the bottom not quite dead. I never did see the cause directly as the tank was very dense with moss.

I immediately ordered the fenbendazole via fishbendazole on amazon. Unfortunately it doesn't give tank dosing values, just says to soak food in it. So I don't have exact values for what I dosed, and as I needed a really tiny amount (for a 1g tank) that makes it even more complicated. I think I managed to get 1mg into a syringe, well shaken and then dosed half the first day, then the other half the next.

Between that and Planaria zero I think I've ensured I have cleared up those threats, as well as wiped out the snails.
 

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Hi!
I just mixed the fenbendazole concentration and treated my tank for hydra for the 1st time. Can I save the leftover mixture if I need to dose again in the coming days? Does it need to be refrigerated?
 
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