Dwarf Angels vs Urchins

[MRRBW]

A replaced my original tuxedo urchin a couple of weeks ago with a beautiful white tuxedo and since it's arrival my Potter's Angel has slowly been picking away at it's spines. It's 1/3 bald at this point. Has anyone seen this behavior before? I've tried to dig around and find something on this but it's a mystery to me at this point. Water params are all within normal and there's plenty for the urchin to eat for it.

 

[MRRBW]

Here he is. He's still quite active and munching away

 

[BlueCursor]

I have an LPS/SPS tank with a Tuxedo, Halloween, and Rock urchin. My Brazilian Flameback is a model citizen in my tank, not touching any coral, except he does pick at my Halloween some. Doesn't seem to be an issue for the Halloween, but he does pick at him some. I haven't seen the Flameback bother the Tuxedo or Rock urchins.

 

[MRRBW]

It's an odd behavior I think from my angel. He doesn't pick at any corals though thankfully, but it's a shame bc I love urchins.

 

[BlueCursor]

If you have a fuge try sticking the urchin there for a while just to give him a rest from the angel.

 

[MRRBW]

If you have a fuge try sticking the urchin there for a while just to give him a rest from the angel.

Unfortunately, I have an old DAS aquarium with an internal box/sump set-up, so no go. It took a trip to Dr Fish store and now is recovering in one of their sump fuges free from attackers. Tough pill to swallow, but a new lesson learned. I've never heard or seen dwarf angels attack urchins. Must have been tasty.

 

[Brew12]

Can you post your chemistry numbers?
Angels "shouldn't" be pulling the spines off an urchin. It is possible it was feeding on something growing on the spines and that the spines were weakened and pulling off.
I seem to remember seeing something about low alk being able to make an urchins spines more brittle and susceptible to damage from feeders.

Maybe @eatbreakfast can weigh in?

 

[MRRBW]

Unfortunately it wasn't eating something else off of it. It was actually nipping and pulling off the needles. I tried to film it, but of course my phone memory was full. Numbers are as follows:

Temp: 78
pH: 7.9
Nitrite, ammonia: 0
Nitrate: 0.3
P04: reads low but it lies to me (constantly trimming hair algae- I have a fuge in some parts of my tank)
Mg: 1340
Cal: 420
Alk: 7
Sal: 1.0255

 

[4FordFamily]

Can you post your chemistry numbers?
Angels "shouldn't" be pulling the spines off an urchin. It is possible it was feeding on something growing on the spines and that the spines were weakened and pulling off.
I seem to remember seeing something about low alk being able to make an urchins spines more brittle and susceptible to damage from feeders.

Maybe @eatbreakfast can weigh in?

X2 this is really not a common behavior. You may just be really unlucky

 

[Eggs]

I have a Potters Angel and a Longspine Urchin and haven't had any issues.

 

[Waters]

I have seen Triggers and some of the larger Wrasses do that, but never a dwarf angel. Definitely odd.

 

[Brew12]

Let's try to bring @eatbreakfast in again...

 

[MRRBW]

I may have an oddball potter's. I don't ever see it nipping at corals, but the urchin was definitely on its menu.