Damn you Hydra!

I swear I start this post at least twice a year, but I have yet to learn it seems! I moved around some fry over the last week, and had some new fry hatch. The first thing I did, was take the newly hatched fry and throw them into the newly emptied tanks. Bad move. The tanks we're infested with hydra, and I believe I lost three quarters of a mixed spawn of rare rainbows!

Warning to the wise, check your fry tanks before dropping new fry into them.

I emptied out the infested plants from the fry tanks, and it looks a lot better. I think I'm going to skip freshly hatched baby brine in these tanks for a while...

Nasty things those hydra. Do you sterilize with a mild bleach solution prior to setup ?

Nope...

I was just going to wipe every surface, and drain the whole tank. Then refill with chlorinated water... we don't have chloramine in Calgary. I usually wait a day, and then its safe to add fry again.

I should mention these are 2.5 gallons tanks, so they aren't much to empty and refill.

I have noticed these green things growing in the bottom of my newly setup aquarium. But they don't really look like hydra right now, only like half cm long green hair.
Do you think this might also be hydra?

hydra is very small, under a centimeter. looks like a hair with tentacles on the end.

I will take a closer look and try to see if it moves..
Can it survive if there are no fish in the tank?
How does it get in the tank?

Hydra can go dormant for a long time with no fish. There are numerous species. Right now, the ones outcompeting all others here are the green ones, my favourites. They are not especially predatory.

I had serious trouble with pale beige ones recently, and they are rainbow slaughterers. "Bows are cute, but they are dumb as can be, and they don't do well with hydra. I eliminate hydra by dumping peroxide into fish free tanks. It bubbles out in a couple of days, and then I do a water change.

There is a large version that is really fierce - it will sting and scar adult fish. I had them really bad when I was breeding Apistogramma in my old house. They were hard to beat.

They come in however these things come - on plants, in spores, with water. I take them for granted, and my green, photosynthesizing ones are a welcome break from their fiercer cousins.

ooooh peroxide, I have that! Its part of my fishkeeper's staple items! we'll see how these dumb rainbows do this week, if they survive I won't peroxide the tank till I can move them.

Thanks for the tip!

I've also heard of Copper being used as treatement as they are sensitive to copper ions.

At first I thought you guys were joking.
I'll have to remember to keep an eye out for it, hate to have the babies hurt.

What about using Fenbendazole? Dog Dewormer? I have used it successfully recently.

Although I am not sure how it affects everything else, I had shrimp and snails in the same tank without serious issues.

Dewormers should work. However, I zapped a tank with way too much H2O2 a few months ago (okay, I spilled it...) and the hydra were eliminated while a few of the snails (dang it) survived. I don't keep shrimp, and I expect it would have destroyed them. Two fry I missed and had given up for dead survived quite well and are now normal, healthy adults.

OK. I checked my tank yesterday night and the horror!!! I have hydra as well!!!! Thank you so much for posting about this here because I was about to move fry in that tank.
I'm going to destroy them today with h2o2. Am also adding a copper wire in there as I heard that combining both methods work very well.

Avoid copper! Yes, it kills Hydra. But it is very hard to remove, and it also sterilizes many species of fish. It is a general biocide with long term effects.
Hobby lore says it gets into silicone and becomes well nigh impossible to get out. I have never seen proof of that, but I have seen copper based meds go from being standards for Ich and Velvet to being hard to find due to bans in several jurisdictions.

BTW - every established tank probably has Hydra. It really only picks off rainbows and the occasional really small fry. Livebearers and killies might take some losees, and the stings might slow growth, but you need a huge infestation for that. If you don't feed a lot of freshly hatched brine shrimp (a wondrous Hydra food) you won't get an overpopulation, and don't have much to worry about.
An infestation makes parts of the tank look like a field of wheat, only the densely growing, swaying grasses are Hydra.

They are a HUGE danger to fry that are not free swimming. Otocincolous Fry as my various attempts have taught me cannot be raised in tanks with ANY hydra. But I have raised some psuedomugil furcatus in a tank with some hydra and they were fine.

Rainbows DO seem to be the most eager to swim into nets for the most part.....

Does anyone have a photo of some hydra for my novice eyes?? I suppose it would be nice if I knew what it looked like?

At one point, I tried, but they are so small.

this link will take you to a picture of a hydra... they are really small as gary said.

Ugly little things!!! Now I remember seeing them in science class a hundred years ago.

I removed the copper wire.
Didn't get the chance to find my h2o2 tho so I think I'm going to buy some.

I used to have the little green hydra in my apistogramma tank where I was raising fry. I tried flubendazole and it did nothing to kill them. I found out that Paraguard works to kill hydra. So I decided to call up Seachem and ask them if this product was safe to use with young fry...they said it was, so I decided to try it. I found that although it did not kill all the hydra it did reduce their numbers significantly. Fortunately the fry were big enough to stop feeding live bbs, so I stopped feeding it to them. This along with the Paraguard treatment made the hydra dissappear. I never saw one after that.

I got h2o2 and blasted it at them.
Today, all I see are little blobs of green where there used to be hydras.
This weekend I'll treat again to make sure and then proceed with a scrape, then water change.
Hoping that wil solve.

There is a good chance that from the blob will come the monster... remember the Disney Hercules movie, when the hero thought he'd killed the hydra and began to relax?

I think I got pictures... they are so small. The online ones may be better, but these are more convenient!
They are on the glass of a tank holding Congochromis sp Cichlids, and Aphyosemion biteniatum one inch juveniles (for comparison purposes, one is included). The tank gets live brine shrimp every second day, to condition the cichlids for possible breeding, and grow the killies.




The one in the middle is Borg. Beside himher is Borg, and just to the right, is Borg. Over to the left is Borg (okay, but they reproduce by cloning and branching - they are immortal beings - all named (by me) Borg. We can drive all hisher incarnations out of our tanks, but we can never kill Borg.)

Thank you Gary. That shows what I would/might see, which is what I wanted to see.