What up dudes? I’m in the same damn boat, so I figured I’d chime in. Just got my 20L planted cycled, got 20 Blue Dream Neos and days later, I’ve got hydra all over. That’s what I get for buying Etsy plants. Worse, some of the females must have been berried on arrival and I have seen a few microscopic shrimplets. I’m pretty sure the Hydra got them, but I’m praying and waiting.
Anyway, I’ve been doing a ton of research and I’ve had to make some tough decisions. I’m nuking from orbit as was previously suggested. I purchased safeguard goat dewormer at the local tractor supply. It’s 100 mg/ml of Fenbendazole in liquid suspension (much easier to mix than the powder. I made a mixture of 1 ml of the dewormer to 9 ml of tank water then the Internet research I read stated to apply 0.25 times your tank volume. My tank is 20 gallons and I’m assuming 2 gallons of substrate and decor, so I dosed 4.5 ml of the mixture (0.25 x 18). I waited 24 hours and saw little effect. I dosed again with the same amount. I’m now at 48 hours and I only see two hydra remaining and they’re tentacles are retracted (a good sign). I’m going to hold off on dosing again and wait another 24 hours to see if remaining hydra die. I see no ill effects in my shrimp yet and I removed all my MTS prior to starting treatment.
God, I never knew shrimp keeping would be this tough and stressful. I can tell you for one thing, I’ll never put another plant in my tank without soaking it in Fenbendazole for at least 24 hours prior again. Good luck to the OP and I’ll let you know how my hydra disaster turns out.