Roly Poly - help identify

brkesar · Aug 26, 2024

I have these black/grey ish looking roly poly in my tank. They do not appear to have eyes (i keep reading if they have eyes they are bad?)
Are these good or bad for the tank? They appear to be hiding out in my Fiji rock.

Currently have soft corals, fish and invertebrates.

Thank you!

SaltySqueeble · Aug 27, 2024

Probably just chitons. Beneficial algae eating mollusks

ISpeakForTheSeas · Aug 27, 2024

Hard to tell from the pics if they're isopods or chitons; chitons will have a rolypoly top and a snail foot; isopods will have a rolypoly top and legs underneath (rolypolys are terrestrial isopods).

The vast majority of chitons and a fair number of isopods are beneficial for our tanks.

brkesar said:
(i keep reading if they have eyes they are bad?)

Some of the common, harmful isopod species have large eyes while most common, good CUC isopod species have small, sometimes difficult to see eyes. This really isn't the best indicator for if they're harmful or not though - the tail of the critter (both top and bottom, but especially the bottom of the tail) and whether or not they roll into a ball like rolypolys do are better indicators.

brkesar · Aug 27, 2024

ISpeakForTheSeas said:
Hard to tell from the pics if they're isopods or chitons; chitons will have a rolypoly top and a snail foot; isopods will have a rolypoly top and legs underneath (rolypolys are terrestrial isopods).

The vast majority of chitons and a fair number of isopods are beneficial for our tanks.

Some of the common, harmful isopod species have large eyes while most common, good CUC isopod species have small, sometimes difficult to see eyes. This really isn't the best indicator for if they're harmful or not though - the tail of the critter (both top and bottom, but especially the bottom of the tail) and whether or not they roll into a ball like rolypolys do are better indicators.

Wow thanks for all the info! I don’t see legs, I think it has a snail bottom - they are so small