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Can anyone help me, I have found quite a few of these little things attached to the inside of my tank, they look like little white worms with tentacles, they are attached to the tank by there end and their tentacles wave about in the water, cant think what they are, the fish are not eating them, the only thing different i have done lately is feed my fish shrimp brine every now and then for a treat, could this be the cause???

HELP HELP HELP

This sounds like a case of Planaria. They often appear from uneaten food in gravel..etc.




Graeme.

Sounds more like hydras.

Read this post.

Are they a danger to my fish??, I have 2 babies about 1 and a half cm long in my other tank that I wanted to add to this tank will they be safe or will they get stung by them and die?

best avoid truly small fish until you rid the plague. fish bigger than 3 cm won't be bothered by them, but I would avoid tiny fry if I were you.

I have found that most people that get these usually haven't changed their water and/or cleaned their gravel in awhile. I would recommend simply doing a 30-40 percent water change and make sure you siphon underneath were decorations and rocks normally sit. These areas are quite often never siphoned and could very well be causing the problem. After that make sure you change your water and siphon gravel once a month and siphon under your decorations at least every 3 months.

I have had these twice in the 20+ years of keeping fish and improving water quality as well as siphoning all of the crap out usually clears these things up. Never had them cause any problems with fish.

Hi!

Hans Frey writes that they appear in all kinds of waters even in the smallest puddles and can often be misided as algae cauz some of them dont show the (visible) tentacles. He advises to use AmmoniumNitrate against them...i have no clue where to get it though. Also they wont stand copper (of course not to be used with fishes in the tank) and Flubenol (a dog flea treatment i think).

Maybe I'm missing something, but I see no hydras in that picture. I see a weak growth of staghorn algae, Compsopogon:
http://mikes-machine.mine.nu/algae_gall ... ghorn_Alga

Hydras look like this: http://www.microscopy-uk.org.uk/mag/imgfeb02/hydra.jpg
and grow up to one inch in length. Usually they grow to about a quarter of that, though.

To be honest I don't think hydras are ever capable of catching fish - I've had tens of thousands of hydras, to the point that all structures were covered in hydra "fur", in aquaria with minute fry, and had no noticeable losses - but they do compete with the fry for food.

I definately have hydras going by the picture you have, they are tiny and white and the moment, I am thinking of getting a fish that eats them as mentioned in one of the replies above.

Sorry ive never seen hydras then sorry for the misleading picture...ill take it out

As for killing hydras, if you feel you absolutely must (the cure may be worse than the disease - you have been warned)...

1) Raising the salinity to or above 3 ppt will kill the hydras in a matter of a few weeks. It will also kill sensitive plants and snails (e.g. apple snails), and conceivably particularly sensitive fish (although I doubt it).
2) Copper nitrate will kill all invertebrates in the tank - lobsters, shrimp, snails, hydras... - but will also kill your plants and depress filter bacteria. And it's toxic to fish.
The "copper coin hooked to battery" method is a variant of this.
3) Formalin, with or without malachite green, as found in e.g. Greenex, will kill hydras. It will also kill snails and depress filter bacteria (I don't care what it says on the box!) and the malachite green may permanently stain silicon. Oh, and both formalin and malachite green are cancerogenous and allergy-inducing to humans.
4) De-worming medications containing fenbendazole, flubendazol, or levamisol will kill the hydras, and will also kill all other soft-bodied organisms in the tank (snails, flatworms, annelids, nematodes, rotifers...) but provided you get dosage right it wont harm fish, crustaceans, filter bacteria, or plants. At least not short-term, long-term is unknown to me.

As is probably obvious, 4) is the method I'd recommend, if you absolutely, positively, feel that you must do something about the hydra. The biggest problem with method 4 is dosage, and I'm afraid I can't help you there. It is quite some time since I last used fenbendazol, and I don't remember dosage.

I dont really want to kill them if I can help it as they look quite nice in the tank, makes it look more sea like, but I would like to keep them from infesting (if they can do that), my other fish dont bother with them and visa versa

If I were you then I'd follow PlecoCrazy's advice and have a good clean around and perform some water changes before trying a chemical route.

As for hydra eating fish, according to Dr C. Emmens writing in "Dr. Axelrod's mini-atlas of freshwater aquarium fishes" (pheww, got it all out!) the Blue or Three-Spot Gourami (T. trichopterus) has an appetite for Hydra. (That's supposed to be a Gourami licking his lips..)