All three fungia plate corals dying

[Mallweiss]

Nothing else in my 90g is affected but these three large polyps all grew from the remnant of a short tentacled green fungia plate that died 3 years ago. So the 3 are clones. Is there a fixed lifespan for these and all three have reached their end? (Or could it be my diamond goby occasionally throwing sand on them?) I remember the mother fungia living about 5 years before the same thing happened.

 

[rabbithazen]

Phosphates

 

[tyler1503]

What are your parameters, lighting and flow like?
Are they dying from the mouth outwards or the edges inwards?

 

[Mallweiss]

They are dying radially. A tear forms from edge to mouth then the skeleton is seen. It adds another radial wedge per week. Parameters are 78 deg salinity 1.024 nitrates 20, alkalinity 8 to 9, calcium 460.

 

[Mallweiss]

Using two Aquaillumination 26, and a Gyre 150 at the top for flow. The plates have been there on the sandbed 1 year without a problem. The goby grew a lot in his first 6 months and is constantly excavating around all three of these, so he's on the list of suspects.

 

[Shaddow_wolf169]

It is a possibility he through sand on them.