help id this pest

[treesmoker]

http://i235.photobucket.com/albums/e...hotos/6048.jpg

[fishnfst]

Funny looks like a gill lice.. Was it on one of your fish?

[GreshamH]

Isopod

[treesmoker]

No, I found a but load of them in a montiopra colony that I bought today.

Somone else told me they were isopods too. Are they predators or irratators?

[Matt_Wandell]

Specifically, a male sphaeromatid isopod.

http://www.reefkeeping.com/issues/2002-05/rs/index.php

Sphaeromatids are small bugs, generally less than a centimeter in length. They are common scavengers in many shallow marine environments, including coral reefs, and they are harmless to reef aquarium inhabitants. They can be recognized immediately by a couple of distinctive characters. First, each individual has the capability to roll into a ball-like terrestrial pill bug. None of the other isopods likely to be found aquaria will be able do that. Second, when examined with a hand lens or magnifying glass, the last pair of appendages of the males are expanded and extend to the rear, like small rudders or the fins on a 1959 Caddy. Females lack these extensions, but if some of the isopods are seen with them, that is usually a good indication that the rest of them are also Sphaeromatids.

They are harmless to fish and corals. They can grow to very high numbers if fed well. They eat detritus, decaying matter, etc.