Lion Shedding?

[rogersbw]

So Ive returned from vacation recently and the day I got back all seemed well. Fish were all normal and eating fine (lion included).

The past few weeks ive been out of town and my mother has been coming every other day to feed the fish (flake food has an autofeeder..so she was just feeding the lion a shrimp).

Anyway...day two (friday) I notice the lion will not eat....doesnt even make an attempt to come up to the surface when food is present...even dropping it by his nose gets no response. Day three (yesterday) same issue...very lethargic actions...basically staying right on the rocks that make up the back of the tank.

Today I notice the wisps/strands of what look like slime...upon further research this sounds like he is shedding? However said research also said generally this is a bad thing and indicates the fish is sick (on top of the fact he already wont eat...thats real bad). Before my departure we did a rather large water change (100G tank...at least 30G changed)...however over the past few weeks and up until friday...the fish have been fine.

All other invertebrates are normal and fine...even the large collector urchin I have is fine. Only other fish is a brown tang..and he is as lively as ever..feeding and acting normally.

PH was a little low 8.0 vs 8.2(normal)...Salinity was a bit high 1.021 vs 1.020(normal)...all other measurements I took (nitrite, nitrate, ammonia) were all normal.

I changed another 10G of water this afternoon and poured some "Stress Coat" into the tank in hopes of helping whatever is hurting my Lion...but I fear its too late. A few years back my first lion developed a similar condition (although much..much worse on the shedding than this one)...and he was dead shortly after. The odd thing is the tang survived whatever killed the lion then too (same tang). Its been in the tank since its inception 3+ years ago...the lion is a recent addition perhaps 9mo ago.

Any idea on what else could cause my lion to go from normal...to this?

[ATJ]

Shedding of the outer layer of skin is not uncommon in lionfish and they will do it periodically. I believe all fish do it (as do amphibians, reptiles and even mammals) but it is more noticeable in lionfish. It may, however, indicate some stress, perhaps something in the water that your test kits don't detect. I recommend you do a large water change (25-50%) and see if you get any improvement. If you don't, it would be wise to move the fish to a treatment tank and give a course of antibiotics.

A pH of 8.0 is within the normal range of natural seawater and you shouldn't worry.

A specific gravity of 1.021 is far too low! Natural seawater on reefs has a specific gravity between 1.025 and 1.028. I am surprised the sea urchin is still alive and I suspect your hydrometer may be inaccurate - I hope so. I recommend you have the hydrometer checked for accuracy (preferably against a refractometer - or better still buy a refractometer) and raise the specific gravity slowly back into the normal range. The easiest way to do this is to replace evaporated water with seawater which will raise the specific gravity gradually.