Hydras... good, bad, or...??

  • Get the NEW AquariaCentral iOS app --> http://itunes.apple.com/app/id1227181058 // Android version will be out soon!

nynikki

"Would you like to play a game?"
Aug 7, 2007
348
0
0
Phoenix
I have read that hydras are a positive sign of the overall health of a tank, so that's good.

I have also read that they will eat fry, I'm not too concerned about this. At the rate my Swords are reproducing, I'll be bringing batches to a friend to feed to his Oscars so if I loose a few along the way, no worries.

I have also read that they will sting my fish...?? Now I've squished one or two with my finger, and seen some of my fishies swim past them with out any ill effect. I have also seen some of the fish try and eat them and spit them out - makes sense - I would imagine if I stuck one in my mouth, I might actually feel it sting too.

I know you are all going to say, reduce feeding, but I have even found them in my QT tank where there was only 1 fish and controlling his food was easy. I've been doing a gravel vac with a 40-50% water change weekly. I'm assuming that I am seeing more now because on Saturday I rearranged some plants and that stirred up the gravel real good.

How do these things come to be in a tank? I added driftwood that I bought at a pet store. I boiled it for hours and left it out in the AZ sun for a week - I'm pretty sure nothing would have survived that. I know I also have nematodes and probably some sort of pod - not sure about these yet, just guessing that's what those tiny white specks are on the glass.

For now I guess I'll up the gravel vacs and try to starve the tank but do I need to be obsessed about getting these things out?
 

tanker

Josh Holloway--Be mine!!!
Sep 1, 2003
7,321
333
116
Calif. SF Bay area
Visit site
Real Name
Jessica
Hydra is not a sign of a good tank, nor a bad one. They could have come with plants, rocks or anything. They normally cannot hurt large fish, and like you said will eat fry. Just for your info most Gouramis will eat them.
 

nynikki

"Would you like to play a game?"
Aug 7, 2007
348
0
0
Phoenix
Hydra is not a sign of a good tank, nor a bad one. They could have come with plants, rocks or anything. They normally cannot hurt large fish, and like you said will eat fry. Just for your info most Gouramis will eat them.
Well that's good to know. But I don't think I have space for any Gouramis I have a female GBR and Albino Bristlenose nose on the way... I'm stocked.
 

spudjnr123

AC Members
Apr 3, 2006
377
4
18
Vacaville, CA
www.flickr.com
Real Name
Taylor
Camera Used
Nikon D610
Actually, Hydras really aren't good or bad in and of themselves. hydras won't hurt any larger fish (i.e. more than 1 cm) and can actually provide a treat for some fish that eat them. They can sting smaller fish, as they have cnidocytes (stining cells) like jelly fish, but they are really too small to hurt large fish.

In terms of water quality, the presence of hydra generally means there are nutrients in the water, and that there is also beneficial bacteria and smaller microorganisms. Because smaller hydra feed on organisms like daphnia and bacteria, they can help to keep bacteria blooms down.

For your tank, I'd say live and let live. They won't really hurt your fish, and they will be a good indicator of water quality.

However, if you see any hydra over 2 cm or so, kill it, they will hurt your fish, as they would then have quite large tentacles which could wrap around and sting fish. until the tentacles are quite long though, they won't be able to grab the fish.
 

Esox lucius

AC Members
Jul 28, 2007
39
0
6
Copper sulphate will also decimate any other inverts in your aquarium and probably won't do your fish any good in the long term either. Hydra are an indication of good water because they can't survive without food, they feed on smaller inverts which themselves require good water quality and require food themselves such as algae or bacteria. So if you add copper sulphate it will kill everything including the inverts and algae which will cause instability and cause more problems than its worth.
 

nynikki

"Would you like to play a game?"
Aug 7, 2007
348
0
0
Phoenix
And I am very fond of the snails that I purchased and wouldn't want to hurt them. I guess as long as they don't start killing or making my fish sick. They are kind of cool to watch. The funny thing is that I have been saying for years that I would love to keep Jelly Fish - The dream was to have an expert come and maintain a floor to ceiling cylinder of them. This obliviously falls way short of the dream!
 
zoomed.com
hikariusa.com
aqaimports.com
Store