What's up with this toadstool?

[Fremlins]

I'd be grateful for any ideas on what's going on with this toadstool, and how to fix it?
As you can see its stalk has basically collapsed.
I've fiddled with the flow and I'm gradually increasing the light intensity although AIUI this is a low-light coral.
I wonder if it could be lack of phosphate? My phosphate levels have crashed - full water parameters (as far as I've measured them) are

Ammonia - 0
Nitrite - 0
Nitrate - 5.0
Phosphate - 0

As I don't have any stony corals yet I've only just started testing for calcium, magnesium and alkalinity:

dKH >8.5
Ca >480
Mg >1500

Another thought that occured to me was lack of iodine, but don't yet have a test for that.

TIA

 

[Donya]

I really doubt this is an iodine or other water parameter thing as far as the coral itself goes, except possibly there being a cause for excess algal growth that is irritating it (which would suck up phosphate). The stalk folding over while the top looks fine is definitely a not normal condition and suggests irritation, physical damage, or even an infection in the base. I would take it out (with the rock it's attached to) to physically inspect. This will stress the coral to a degree but it will be hard to diagnose otherwise. If it is damaged or being parasitized by something growing on and/or consuming the tissue, then you would need to frag it just above where the healthy pink stalk tissue starts. Healthy tissue should be fairly firm for the base assuming the coral is retracted (which it will likely do when you poke it). If it's squishy where the algae is but firm above that then there is some decay happening and it should definitely be fragged right away before the problem spreads.

The algal growth on the base is not a good thing. A small amount right at the bottom is one thing but this appears to be flourishing and spreading up the stalk. While rare, some algaes can manage to get growing into leather coral tissues and cause decay as they spread. The algal growth could also be just a secondary issue because debris is building up on it. Either way I would remove, inspect, and try to gently wipe it off with a paper towel wet with tank water to see what the state of the tissue is underneath.

Normally snails and other CUC animals like small hermits would help avoid algal growth in places like coral bases by picking it away before it gets that well established.

 

[Colin_T]

I wonder if it could be lack of phosphate?

Phosphates don't naturally occur in large amounts in waterways/ oceans. There shouldn't be any in the aquarium water.

 

[Fremlins]

I really doubt this is an iodine or other water parameter thing as far as the coral itself goes, except possibly there being a cause for excess algal growth that is irritating it (which would suck up phosphate). The stalk folding over while the top looks fine is definitely a not normal condition and suggests irritation, physical damage, or even an infection in the base. I would take it out (with the rock it's attached to) to physically inspect. This will stress the coral to a degree but it will be hard to diagnose otherwise. If it is damaged or being parasitized by something growing on and/or consuming the tissue, then you would need to frag it just above where the healthy pink stalk tissue starts. Healthy tissue should be fairly firm for the base assuming the coral is retracted (which it will likely do when you poke it). If it's squishy where the algae is but firm above that then there is some decay happening and it should definitely be fragged right away before the problem spreads.

The algal growth on the base is not a good thing. A small amount right at the bottom is one thing but this appears to be flourishing and spreading up the stalk. While rare, some algaes can manage to get growing into leather coral tissues and cause decay as they spread. The algal growth could also be just a secondary issue because debris is building up on it. Either way I would remove, inspect, and try to gently wipe it off with a paper towel wet with tank water to see what the state of the tissue is underneath.

Normally snails and other CUC animals like small hermits would help avoid algal growth in places like coral bases by picking it away before it gets that well established.

Thank you!
Interestingly the algae has died back a lot already - at one point the base was covered in brown algae, most of which I was able to brush away, and my snails and hermits have nibbled most of the rest. It isn't squishy.
I think I may leave the CUC to get on with it for a few days more and then I may frag it. Bit nervous about that as it's not something I've done before!

 

[Fremlins]

Phosphates don't naturally occur in large amounts in waterways/ oceans. There shouldn't be any in the aquarium water.

Thanks.
I thought the ideal level for LPS was around 0.05 and 0.05 for SPS? I mean it's academic as I haven't got any LPS or SPS yet but was I wrong about that?

 

[Fremlins]

Thanks.
I thought the ideal level for LPS was around 0.05 and 0.05 for SPS? I mean it's academic as I haven't got any LPS or SPS yet but was I wrong about that?

Sorry, that should be 0.03 for SPS

 

[Colin_T]

As far as I know you want minimal nutrients in coral or invert tanks because they don't tolerate anything really well. The Queensland government has strict limitations on phosphate use (for fertilisers on farms) due to runoff into the Great Barrier Reef because it encourages algae to grow on the corals and smother them. So unless there has been new research in the last few years saying corals need phosphates, I would avoid adding it to tanks.

 

[Donya]

Thanks.
I thought the ideal level for LPS was around 0.05 and 0.05 for SPS? I mean it's academic as I haven't got any LPS or SPS yet but was I wrong about that?

Think of it as the ideal value quotes for things like nitrate and phosphate being <=x rather than =x exactly. In many tanks it's just not possible to get 0 phosphate, so there are minimum thresholds given. I don't recall offhand if 0.05ppm is right or not but lower is better because phosphate contributes to increased nuisance algae growth if nothing else. In a very general sense, SPS are often thought to be more sensitive to high phosphate than others. I don't keep SPS so I can't vouch for that one way or the other, it's just what I've heard from fellow hobbyists who keep them. However, from the same sources, SPS are just more sensitive about a lot of things, not strictly phosphate - lighting is another thing that's a bigger deal for most of them than for most LPS & softies. Anyway, as far as phosphate goes, personally I have had various leather corals with really bad bouts of phosphate levels in the past and they completely didn't care so log as the CUC kept the algae from blanketing them.

 

[Donya]

I think I may leave the CUC to get on with it for a few days more and then I may frag it. Bit nervous about that as it's not something I've done before!

Tissue necrosis can progress very rapidly and without warning in corals. A small coral with a bad infection can go from being salvageable to being a pool of goop overnight although toadstools and leathers are less likely to do that than LPS/SPS. Keep a very close eye on it. If you see any spread at all of the deflated area, take it out and cut it with a sharp knife where the tissue is still healthy - use a singe blade, not scissors which can crush tissue and cause more problems on thick areas. The cut piece should be kept away from the tank but in tank water for an hour or so, then set in an area of low flow on a clean area of rock so it can re-attach (assuming there is nothing that can knock it around like a larger hermit - in which case you would need to use the plastic toothpick pinning method and then glue the toothpick down).

 

[Colin_T]

@Donya, what about super gluing the coral to a rock after it's been cut?
I know you can super glue hard corals, but can you glue soft corals?

 

[Donya]

@Donya, what about super gluing the coral to a rock after it's been cut?
I know you can super glue hard corals, but can you glue soft corals?

Unfortunately not really! In rare instances you can if the base is really dense and mostly large sclerites, but otherwise they will almost always tear free, either by sliming so the glue never really sticks or changing shape to pry themselves away, even if they damage themselves further in the process. I even had one cabbage leather frag tear itself free of a plastic toothpick I put too close to the edge by alternately inflating and deflating the tissue around it. Softies can be really moody about attaching; I always find it easier to just put them in a basket with some rubble and let them decide how they want to sit.