Tiny shrimps in my tank? see pic!

[delmore]

The focus is soft, but it looks like a tiny shrimp. When it is on it's side, with just a little water, something near the eyes keeps moving. I captured several of these creatures when I vacuumed the gravel. They are between 1/16" and 1/8" long, and have large black eyes.

http://www.wu7.net/shrimp02.jpg

[OrionGirl]

Looks like a scud. Decent pic--they are speedy buggers!

[Geeky1]

http://www-personal.umich.edu/~mjwiley/www311/gammarus.jpg

They're gammarus... this (http://www.bcadventure.com/adventure/angling/bugs/shrimp/shrimp.phtml) page has some good info on them.

//Edit
I should probably mention that apparently "Scud" is one of the common names for Gammarus... I didn't know that...

[Dangerdoll]

definitely scuds...... I didn't know they could be in freshwater too... interesting....

[delmore]

Thanks for the replies -- very interesting! I've had them for the last two or three years in my tanks, and have never seen them larger than 1/8 of an inch. When I vacuum the gravel they do their best to resist the suction.

Either the corys or other fish are eating them before they grow larger, or perhaps they are a species from SE Asia or someplace, since the Hyella and scuds are much larger.

I'll return them to the tank. I don't think they'll do much harm, and they might be a nice little snack for the fish.

[Geeky1]

The largest gammarus I've ever caught is 1/4" (we're talking about wild ones here... I occasionally go down to Carmel (near Monterey CA) and look for sticklebacks & stuff in the Carmel river. Anyhow, the largest ones I've seen are about 1/4", and most aren't any bigger than 1/8".

I'm not sure your fish will eat them though. They have very, very, VERY tough shells, and from what I've read, not much other than adults of the various big cichlids (Oscars, Discus, Angels, etc.) have jaws strong enough to crunch them.

However, like you said, they're probably not doing any harm. They can carry diseases, but if they've been in there for years and you haven't had a problem, I doubt you're going to have one now. Besides, they're scavengers, and in the wild at least, they burrow into the sand a short ways, so they're probably at least somewhat beneficial.

I wouldn't worry about it.

[OrionGirl]

Since they are likely reproducing in your tank, the larvae are definitely a tasty treat for smaller fish, and larger fish will eat them as well if they can. Actually a good sign for 'condition normal'--an abundance of them can indicate over feeding, just as with snails.

[SimonWoodstock]

how do you suppose they got there originally? if they do no harm seems like an interesting creature to have in you tank.

[Geeky1]

Outside of intentional introduction, I've never seen them in a tank. However, I've read it's possible for them to come in with live plants (I always wash mine to remove snails, and I've never seen any come off any of my plants) Depending on how big the babies are, they might also be able to come in with new fish (if you just dump the water from the LFS's tank into yours, they may come out with it)

So either on plants or in water from another tank.

[delmore]

Originally posted by SimonWoodstock
how do you suppose they got there originally? if they do no harm seems like an interesting creature to have in you tank.

*at 4:30 PM EST The server with the pic is down. I should be up soon.*

I have no idea where they came from. I didn't have live plants when I first got them, so they must have hitched a ride with fish.

I never collected rocks or driftwood from streams or ponds.

[tricksterpup]

Delmore,
Definatly Scuds, and I am with Orion Girl on this, they are excellent live food for your fish. Keep them as long as you can. I have a container that I am actually raising them in. I just recently placed some in a het tank of mine to start a culture going. :)
But they are a fun little creature to have in your tanks.
good luck with them.


jim

[delmore]

I returned the 4 scuds to the tank. Now during the weekly cleaning I'll have to make sure that I don't vacuum up the albino corys (it happened once...) AND the scuds!