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Discussion Starter · #1 ·
What the heck is this? It seems pretty harmless now but it seems to be slowly growing in numbers. It first appeared a week ago just after I redid about half of my tank. I think this may only be the first wave. Water change tonight.
 

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First photo i've ever seen of a Hydra. I think they will kill baby fish. I think larger fish may eat them. That's something you've got to get rid of. How did you get it?

Steve Pituch
 

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Discussion Starter · #3 ·
No idea where it came from. This doesn't sound good. So is it an algae or a parasite? It may have detected me because it's not there any more. Research time.
 

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OK, well I didn't mean to alarm you. Take a lot of pictures as at least to me they are rare. They will devour fish up to 3/16 inch long, so livelearers are generally not threatened. However, they shoot out those tentacles and hit their prey like a harpoon, then drag it to their stomach and become very squat while they are digesting their prey. Some gouramies will eat them if they are not fed. I would think flag fish might eat them too. They get around pretty well also with that one sticky foot and the tentacles they slowly somersalt to their destination. Apparently a big water change sometimes kills them. Five grains per gallon of ammonium nitrate willl kill them too but we don't want to put ammonium in the tank unless you remove all the fish, since ammonia kills.

Most of this was in the Innes book, 1966 ed.

Steve Pituch
 

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Fluke tabs will get rid of them in a couple of days. Don't feed any daphnia, because they will multiply like crazy. Look out for other meds because they can stain your tank.
 

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Discussion Starter · #6 ·
Thanks Steve. I'm going to do a water change tonight, and I guess every few days for a while. Will that starve the remaining hydra? I dread trying to gather up all the fish but the ammonium nitrate idea could be a future option. How will the plants handle it? So far most of the research that I have done concerns itself with tanks with fry and not planted tanks.
Any other ideas are appreciated.
 

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Well the Innes book was written in the 1930s, so there are probably better ways. Actually the instructions say remove the fish for the water change, but remove "nothing" for the ammonium nitrate treatment. Very strange. If the ammonium was less then a few tenths of a ppm it probably would be alright. Amonium nitrate is a standard ingredient of fertilizer but I don't know if you can easily buy it. I would check at the Plant Nursery. I think they might have blown up the Oklahoma federal building with it. According to Walstad, plants prefer ammonium to nitrates so it shouldn't hurt the plants. I'm thinking that a water change and a chloramine disabler will make the water safe for fish. Actually I don't know if ammonium is bad for fish, but if it was converted to ammonia it would be deadly. I also don't know how to convert grains to grams and what the ammonium concentration would be.

Steve
 

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Discussion Starter · #8 ·
Your info is so appreciated. These are strange creepy little creatures. The water change took some out but I still see a few. Will fluke tabs have any negative effect on the plants, fish, or shrimp? I think my LFS will get a visit tomorrow.
 

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It was actually recommended from another plant board. I didn't have any problems with using it. Clout is the actual medication that is made for the hydra infestation, by aquarium pharmaceuticals I believe. But even though fluke tabs say nothing about hydras on the packaging, it actually was said to be more effective. Ask the store clerk, because they usually have it hidden. Or you might want to call around, just in case its hard to find.
 

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Hydra is just as bad or worse than algae, especially if you use lots of live foods. Hydra made their way into my tanks about a year ago and have taken a firm foothold despite all attempts to expell them. The fastest way for hydra to spread and infest a tank is by introducing small live foods like BBS or moina. This becomes a huge problem for those who breed fish and rear young. I have found chemicals to be pretty much useless especially in planted tanks. Remember that hydra are inverts, so anything that kills them will harm other inverts like shrimp.

I have tried using salt with a lot of success, but this was in my bare bottom rearing tanks. Several species of Gourami are known to eat Hydra so if your tank allows it, you can introduce these fish to your tank. They won't eradicate them completely but will definitely keep them in check.

The coolest way to get rid of them, err get rid of most of them... is to electricute the tank using a 6 volt battery. Suggested to me by a friend, I did this to one of my small planted tanks. I took out all the fish and hooked up wires to the battery terminals and dropped the wire ends in the tank. It did not take long for them to die. I did see a few hydra pop up a few months later.

I have to admit, these thing are pretty cool, I especially like to watch them catch and eat BBS but they do hurt fry and young fish. I don't think they can actually kill fry. If anything, constant stinging probably weakens the fish, making them susceptible to disease.
 

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Discussion Starter · #12 ·
Here is some interesting reading that I found regarding my new little "monsters." It figures I have to get critters in my tank that are actually named after a Greek monster.
I wonder what they could be eating in my tank. I have no fry (maybe some shrimp eggs) and I feed the fish flake food only. Hmmm... Maybe they will starve. Maybe they have been dormant in my tank. I have done some big changes regarding KH, GH, and PH. All are higher because I am installing a new Co2 system and I am trying new methods to keep these water parameters. I guess I should start to cycle a quarantine tank for my fish and shrimp in case these things start to grow in numbers.

http://members.optushome.com.au/chelmon/Hydra.htm
http://home.clara.net/xenotoca/hydra.htm
http://216.239.51.104/search?q=cach...zoleArticle.pdf+aquarium+hydra&hl=en&ie=UTF-8
 
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