Too many isopods???

[Canarygirl]

Hi

Every night when I peek in my tank with the flashlight it seems like my rocks are alive with scattering, big, creepy crawley isopods. They're huge! Is it problematic to have lots and lots of these in the tank? Do they prey on copepods, for example? If they do then I probably have barely any left in my tank!

Are there any fish or nighttime predators that eat isopods but are reef safe? (if that's not an contradiction)

[ludnix]

I know the addition of a flame hawkfish would reduce your pod count dramatically. As liveaquaria.com says, their temperament is semi-agressive though. The flame hawkfish I have will occasionally chase around my royal gramma but other than that it hasn't done any harm. It's currently in a tank with two small true perculas, a royal gramma and 2 bengai cardinals

http://liveaquaria.com/product/prod_display.cfm?pcatid=193&N=0

[Icefire]

got a pic? some isopod can kill fish

[lecher]

Are you sure they are not amphipods? If so they are beneficial.

[techreef]

a good number of wrasses will also eat pods. for your sake, having gone through cirolanid isopods in my tank, i hope you have amphipods, not isopods!

[fatdaddy]

My mandarin lives off of these. It's looking fat and happy lately, so I've been thinking of getting him a mate.

[Whisperer]

My mandarin also catches some once in a while. The problem is that these amphipods are nocturnal. They come out when most fish are sleeping. My yellow wrasse, gramma, sergeant major will grab anyone that happen to wander away from their hiding place in the daytime. I get plenty of them in the filter socks and toss them back in the sump (BTW, I am talking about gammarus shrimps here). If your tank is really overpopulated, consider a nocturnal hunting fish. I think cardinal fishes are nocturnal hunters from what I've seen in my tank.

[danch]

Assuming these are munnid isopods (as seen in this article http://www.reefkeeping.com/issues/2004-08/rs/index.php), there's no real problem with having a bunch of them - they're thought to be herbivores, and I know my extensive population of them do like to hang out on my nearly as extensive algae films.

Now "Big, crawly" makes me think that what you're seeing might be amphipods (munnid isopods just aren't big enough to creep me out, but I've seen a couple of amphipods that started to give me the heeby-jeebies) (http://www.reefkeeping.com/issues/2004-09/rs/index.php), which are also harmless.

The main point is, if you've got enough of them in a new tank to worry you, consider what they're eating in that new tank to bloom like that. Odds are the only things that will support these populations are dead material on the rocks, bacteria decomposing the dead material, or algae. At some point, they'll run out of that food and the population will die off. There might be a few predators hunting the smaller pods, but that will settle itself as well.

[fatdaddy]

I'm fairly certain that I have isopods.

I left one tank fallow for 6 months and these guys were out all day long under MH lighting. I never fed the tank, so I think they lived on the ditritus and/or algae. They even wander on the sand.

On my other tank, I rarely see them during the day. The pseudochromis, mandarin, and damsels hunt them, but if you turn over any rock, it's crawling with them.

They are harmless or even beneficial and give the fish hours of entertainment and nutrition.

[Canarygirl]

Thanks for your responses, everyone. This was very helpful. These things are clearly amphipods.