Help ID isopod

Nick Steele

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So I’ve been see this weird looking isopod thing in my tank when looking at night and it just gave me the creeps! I’ve planned to catch it just haven’t got around to it and today while siphoning flatworms out it showed itself so I grabbed it!

It’s weird looking and it somewhat a reddish color to its body. I haven’t seen it curl up at all but I also don’t want to play with it cause it freaks me out lol.

Any help is appreciated!

IMG_9492.jpeg
IMG_9493.jpeg
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ISpeakForTheSeas

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So I’ve been see this weird looking isopod thing in my tank when looking at night and it just gave me the creeps! I’ve planned to catch it just haven’t got around to it and today while siphoning flatworms out it showed itself so I grabbed it!

It’s weird looking and it somewhat a reddish color to its body. I haven’t seen it curl up at all but I also don’t want to play with it cause it freaks me out lol.

Any help is appreciated!

IMG_9492.jpeg
IMG_9493.jpeg
IMG_9495.jpeg
With the big eyes, it's probably a Cirolanid isopod or relative - so most likely not a keeper - but clear pics of the underside of the back half of the body (mostly the tail) and/or a description of if the underside is flat or rounded could help with saying for sure.
 
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Nick Steele

Nick Steele

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So woke up this morning and I seen two attached to my new clownfish. Proceeded with a freshwater dip and they almost instantly feel off and fish were added back to tank. I will keep an eye out for any more and continue with freshwater dips if on fish.

Backside looked roundish to me and when dead kind of curled up. But it was attached to fish so it’s a no for me no matter what! Plus I did have a mysterious tailspot blenny death a few weeks ago so maybe that caused it.
 

eliaslikesfish

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When you know what you’re looking for, telling the difference between a Cirolanid (bad) versus a Sphaeromatid (good) becomes a lot easier. It's all in the eyes.....
The eyes of the Cirolanid are generally closer together and towards the front of the head. They always look angry because of the slant of their eyes.

The Sphaeromatid eyes are generally more to the side of the head. Looking at the side by side pictures I've included of both isopods may help.
Sphaeromatids also have the common name "Roly Poly" as they, unlike the Cirolanid, roll up in a defensive position when they feel threatened. The Ciralonids cannot do this.

Where you find them may also help decipher which is which. If it's attached to your fish, it's probably pretty safe to say it's a Cirolanid. If there are a few scurrying around when you lift up a rock, lean towards it being a Sphaeromatid.

IMG_3977.jpeg
pic creds to LionFishLair.com of course
 
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ISpeakForTheSeas

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But it was attached to fish so it’s a no for me no matter what! Plus I did have a mysterious tailspot blenny death a few weeks ago so maybe that caused it.
I wouldn't expect these to kill a fish, but, yeah, if they're attaching to a fish, that's a parasite, and you don't want it.
When you know what your looking for, telling the difference between a Cirolanid (bad) versus a Sphaeromatid (good) becomes a lot easier. It's all in the eyes.....
The eyes of the Cirolanid are generally closer together and towards the front of the head. They always look angry because of the slant of their eyes. Think of them as needing to look forward to "capture" it's prey.
The Sphaeromatid eyes are generally more to the side of the head. They always remind me of baby seals with their big black harmless looking eyes. Looking at the side by side pictures I've included of both isopods may help with this "visualization". smile emoticon
Sphaeromatids also have the common name "Roly Poly" as they, unlike the Cirolanid, roll up in a defensive position when they feel threatened. The Ciralonids cannot do this. Think of it like this: the Ciralonid is mean and will never back down from a fight. The innocent little Sphaeromatid rolls up in a tiny little ball saying "Please, don't hurt me!".
Where you find them may also help decipher which is which. If it's attached to your fish, it's probably pretty safe to say it's a Cirolanid. If there are a few scurrying around when you lift up a rock, lean towards it being a Sphaeromatid.

IMG_3977.jpeg
pic creds to LionFishLair.com of course
Yeah, this is a good general tip/guide, but there are definitely a number of Cirolanid pods (and some Aegid pods too) with smaller eyes that look more like Sphaeromatids, and there are a number of Sphaeromatids that can't curl into a ball either (though if it does curl, it is a Sphaeromatid) - the tail in the pic quoted above is actually as much of a giveaway as the huge eyes, as only male Sphaeromatids have those huge prongs on the side of the tail (the elongated uropods next to the telson).
 

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