Hole and possible PM ID

[Jukka]

Any diagnose for this hole in the middle in both my new derasa?
It also seems like pinched mantle?

Pictures

 

[a4twenty]

i don't see any PM but i do see the hole.

did you drop any salt on it?

what fish / inverts. do you have?

what are your parameters?

what do you dose? and how

once we figure out what caused the hole and how to prevent it from happening again the clam should be able to heal

 

[Jukka]

Salt was not dropped on them. There are two different derasa in those pirtures and both have similar hole. I have had them for a week now.

Fish are: A. sohal, A. leucosternon, Zebrasoma xanthurum, G. bellus, P. imperator, midas blenny and decora. I haven't seen any of them bother them.

Moving inverts are Ophiarachna incrassata, diadema setosum, tripneustes gratilla.

Parameters:
- pH 8.3 - 8.4
- dkH 10
- Ca 400+
- NO3 ~10
- SG 1.025
- PO4 low
- light above them 400W 14kK

Dosing:
- Ca/co2 reactor
- Kalkwasser
- Activated carbon, replaced 1kg today
- had Fauna Marin Power phos, but took it all away today
- Fauna Marin coral food, ultra min and ultra organig
- all water through RO/DI

 

[mbbuna]

its hard to tell from the photos but the hole looks like a secondary ex current siphon. uncommon but not unheard of.

 

[skinz78]

did the clams have this hole when you bought them
They look healthy, just have 3 holes

 

[a4twenty]

<a href=showthread.php?s=&postid=11336780#post11336780 target=_blank>Originally posted</a> by Jukka
P. imperator

i would keep a very close eye on him, take a look at this

 

[a4twenty]

<a href=showthread.php?s=&postid=11336780#post11336780 target=_blank>Originally posted</a> by Jukka
Ophiarachna incrassata

when i quickly looked through your list i thought this was a regular brittle star. i would also keep an eye on him, they are a predator that can / will catch and eat fish. we more commonly call it "green death" or "green terror", they are not friendly.