Strange little creatures in my 5g

[kvr]

I have this small (5g) growout tank that I keep ready in case I'd need it. It's planted with some java fern and vesicularia dubyana. Temperature is around 75 and the 15W light is on for about 10 hours.

I added a Eichhornia crassipes (''Water hyacinth'') that I had outside (cause it wouldn't survive the winter otherwise). i didn't rinse the plant or anything and added it to the tank.

Immediately, a lot of small creatures came crowling out of the roots of this plant, and I have no idea of what they are.
The one in the picture looks like it, but I'm not sure if it is exactly the same :
http://allserv.rug.ac.be/~kvrompae/fish/creature.jpg

I had three guppy fry in there, and after two days, they died (can't find them anywhere). Can these creatures have brought a disease in my tank, or would they eat little fry ?

[Serrateeth_2002]

these animals looks like sea roaches.

[kvr]

Originally posted by Serrateeth_2002
these animals looks like sea roaches.

Sea ? As in marine animals :confused:

[Faramir]

It is the common water louse - Asellus. Fish eat them. Totally harmless - they would not have touched the guppy fry. They live on detritus, so technically they'd actually make good scavangers.

[kvr]

Are they known to carry diseases ?

[Serrateeth_2002]

Originally posted by kvr


Sea ? As in marine animals :confused:

Sea roaches are marine relatives of water louses.i think,guppy fry were probably eaten by their own parents.

[wetmanNY]

Score again, Faramir!

I was stumped. I was looking at all those little armored segments and too many feet and all I could think of was "isopod". I was right too, in a general way. Check these gorgeous color pix! http://home.t-online.de/home/ghstanjek/wasassl.htm