Parasites or Good Bugs?

[Beverly]

At the end of October, we lost all the new fish we put into our 72 gal bowfront The tank is now being fed, but is going to be fallow for 8 weeks. Loss of fish was possibly due to velvet, internal parasites, or external parasites. We really don't know which, and it could be all of the above.

Had the flashlights out tonight and happened to see a strange looking bug swimming about near the front glass. Looked like some kind of isopod, but I couldn't say for sure what the heck it was. Caught it with the turkey baster and put it in a cup. Kept looking in the tank and found two more on the sandbed, one of which had just emerged from the sand. All three are now in the cup pending ID.

Here are the best photos of these bugs. They are about 1/8th of an inch in length. All three are walking about on the bottom of the cup and sometimes swimming around.








Any idea if they are parasitic or just natural fauna to be found in a healthy tank?

TIA.

[Quinn]

I wouldn't trust those things for a second.

http://atiniui.nhm.org/presentations...zer/sld003.htm

They look rather like the one on the bottom left.

I would doubt, however, that these are responsible for the death of your angels.

[Jason McK]

Check this out I think this is your guy a Marine pill bug.

http://www.museum.vic.gov.au/crust/pillbugs.html

Sounds harmless

J

[Aquattro]

I beleive isopods are carnivorous, so maybe put a bit of fresh fish in the cup and see what the do. If they eat it, rock them!

[Bartman]

Looks like an urchin larvae. Does it move forward with the round end or the pointy bits?

[Beverly]

Quinn,

I don't trust these bugs either, mostly because they are capable of swimming. If they were bottom feeders, they would have no need to swim anywhere because there is an almost endless supply of ocean bottom to live in/on.

These look like adults to me. Maybe their larvae could have had a hand in doing in my angels.

J,

Kind of looks like a harmless pill bug, doesn't it? They even roll up like a pill bug would. But there are thousands of isopod species, some detritus/dead-live algae eaters, and then there's the parasitic ones. There are so few diagrams and photos of the various species that, dang, I need to err on the side of caution here and suspect these bugs to be baddies.

Brad,

Judging from the research generated by the above links, plus a serious bunch of Google searches, I've found out the not all isopods are parasitic. But can't tell about these guys and I don't want to take any chances. Don't think I'll rock 'em though. Just put 'em in the freezer

Did add some frozen food with fish as a major component. The bugs didn't go near it at first, but are now eating it with gusto. I think a live fish would be a better test, but I don't think I'm going to set up a tank for that test. Hmm. Maybe I might, though....

Bartman,

The move in a forward manner, leading with the eyes.

Whatever they are, we're going to watch that tank like hawks with our flashlights. If they are parasitic, there is a period of time when they can live without hosts. After that, they will naturally die. May have to extend the fallow period to make sure that if these bugs are parasitic that they and their larvae are all gone before the new fish arrive. That's going to be a tall order, especially not knowing their life cycle and what the larvae look like

Thanks, all, for your input

[Beverly]

Well, I decided to set up a 5 gal on Sunday, put LR and a bit of sandbed from tanks that were healthy, put the bugs in it and got a green chromis to test the bugs for parasitism. Have also been adding more of the bugs from the infected tank when we find them. So far, the chromis is doing well.

Have marked the calendar for a 5 week quarantine time to give the bugs a chance to infect the chromis if they are indeed parasites.

Will post a follow up later.

[Quinn]

I thought all marine isopods were omnivorous...

Bev you should get a wee little nano and set up an isopod species tank.

[Beverly]

Quinn,

From the research I did on isopods, beginning with the two links provided, I discovered that some are parasitic, some are detritous eaters while others are live and dead algae eaters. Isopods are a mixed bag of feeders, basically.

Was looking in the 72 gal where the bugs originated last night. Did not see any of the bugs in the photos, but did see hundreds of way smaller bugs on the uncleaned glass. Most were on the glass, but some swam into the water column. These bugs were smaller than a pin head, but I am thinking they might be offspring of the bugs we caught for the 5g test tank. Will be looking for them over the next few nights to see how they grow, and possibly add some of these bugs to the test tank.

[Quinn]

I think what you're looking at there would be copepods.