White creatures on aquarium glass

[Winston]

Please help! I have an established aquarium of 16 months. Noticed last evening approximately 15-20 disc-like creatures stuck to the aquarium glass. They are not on fish, rocks, or plants. When viewed with a magnifying glass, they seem to look "crab-like" and move very slowly up the glass by means of many tiny "feet." When I reach in to actually touch one, they feel very hard and spiny. What are these? How do I treat them? Any help would be appreciated.

[ChilDawg]

I would lean toward hydras on that one. They are not harmful except to fry, but, if you want to rid a tank of them, a dwarf gourami would be a good addition. Be cautious, though, since dwarf gouramies also make meals of beneficial snails!

[Winston]

Thanks for your help. I will go on that assumption.

[ChilDawg]

Do they look like this one?

http://www.ucmp.berkeley.edu/cnidaria/hydrozoa.html


I am starting to wonder, as I thought that hydroids were sessile.

[ChilDawg]

Golly, I think that I read the white creatures on glass and nothing else. Try looking up amphipods and see if they are what is on your glass. I apologize fully for any confusion I may have caused!

[Winston]

No problem. I'm really confused with this one as well. They look nothing like the picture you posted. They are rounded and disc-like in shape. They stick to the glass with some sort of suction. If you have any other ideas, please let me know. Thanks again!

[Tom.E]

Hydra are not hard or spiny. Are you assuming they have ‘feet’ because they move or are you actually seeing legs (6 perhaps)? It sure sounds like you’re describing a limpet.


Tom

[Winston]

When I view them with a magnifying glass, they actually have some sort of "feet," but there are definitely more than 6! Can't get a good enough look to count them, but they move about very slowly, all the while "suctioned" to the glass. They actually look like white crabs and are hard or "spiny" to the touch. Any other suggestions would be appreciated. Thanks.

[OrionGirl]

http://edis.ifas.ufl.edu/FA041

Check out Figure 24, argulus, or common water louse. If this is your critter, you will want to treat the fish. There aren't very many crustacean parasites in the FW side, and if you don't see them on the fish, you should be okay. Check http://www.skepticalaquarist.com/ under Invertebrates/Arthropods for additional possibilities.

[VoodooChild]

I had planarian worms a great while ago, and they were very similar to how you've described them. They never really seemed to be a problem for the fish but never did go away. I took the tank down eventually and that was the end of them. I did treat the tank with Clout, which didn't seem to bother them but knocked off all of my neons.

[Winston]

Thanks for your suggestions. I am going to the LFS today to see if they have any clues and what I can get to get rid of them.

[CrohnieBoy]

Winston:

Sounds like hydra to me. I just noticed them in my tank today. I found a web site that was helpful describing them, their habits, and possible irradication techniques. According to what I was reading, they can move.

http://members.optushome.com.au/chelmon/Hydra.htm


Hope this helps.

[blitzen25bm]

i had those. are they kind of oval shaped and stuck on glass? i scraped them all off but kept getting more so i added aquarium salt. just add some gradually over a few days as much as your fish can tolorate and they were gone in aobut a week. -john

[Winston]

Thanks to everyone for your help and suggestions. As I thought, the LFS wasn't ANY help at all. They don't seem to have a clue about much of anything. Anyway...I will try the salt and see if that helps. Again, thanks so much for all your reply(s). This is a great "help" site.