Why is this coral sulking?

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Dave Wolfenden offers guidance to a PFK reader whose new coral refuses to come out...
 

Q. I have a problem with my newly-purchased green Hammer coral. When it was in the bag from the shop it produced a stringy mucous. I drip fed the new water into the bag to acclimatise it, but it just won't come out.

I placed it sort of horizontally on a rock with putty and I have 4 x T5 tubes, two blue and one white, plus a Red Sea pink! The pink was added at the same time as the coral — it wouldn't be detrimental at all, would it? It makes the tank look lovely?

All my other corals are doing great.

Jamie, email

A. Hammer corals (Euphyllia) can often 'sulk' for a variety of reasons, and it’s quite common for them to react poorly to shipping if they’ve been handled badly or if they have been broken off a larger colony. Watch out for possible signs of infection ('brown jelly disease' or BJD being a condition to look for, which seems to be bacterial in origin). This is characterised by a gelatinous mass around the living tissue and if noted, the coral should be removed immediately. Examine the Hammer closely, and it’s worth lifting it out to give it a quick sniff — BJD has a characteristic smell of decay.

I’m assuming that your water parameters are within the ideal range, as judging by your photo the other corals are looking great. Even so, I’d check them, and ensure that nitrates, phosphates and calcium are at optimal levels. This includes less than 10ppm for nitrates, 400-450ppm for calcium and as near zero as possible for phosphate.

After closely checking the Hammer, I’d move it. Euphyllia are often quite finicky with regards to water movement, and if flow isn’t just right, the polyps may remain retracted. Aim for moderate flow, and preferably not from just one direction. In view of the ability of these corals to exhibit aggression, thanks to their sweeper tentacles, don’t place it too near other corals. Once it’s moved, leave it for several days to settle down before re-evaluating.

Finally, have you tried feeding it? Try offering small pieces of chopped meaty foods, or perhaps frozen Artemia to see if this will encourage polyp extension.

The pink T5 should be just fine, and these can give a very nice look to the aquarium. However, monitor all the inhabitants after altering the lighting for several weeks to establish that they aren’t reacting badly. If lighting isn’t sufficient, you may find that polyp extension increases as the corals seek out more intense illumination. If this is the case, I’d revert back to the original lighting.

Dave Wolfenden

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