How can you recognize this condition? What can be done about it (if anything)?
Well, some of this is going to sound strange, but here goes. I'll use my most recent experience as an example. Most of my anthias are a few years old. Even the newest ones are over a year old. Nothing new, no finicky eaters. One night I feed them, everything is normal, they eat like pigs, and they are acting "normal". With respect to how they act - it's tough to describe, but you just know, after watching these fish day in and day out, for years, what "normal acting" is... know what I mean?
Well, the next day I get home from work and immediately know something is wrong. I don't see all the anthias swimming around as usual, and they certainly don't all flutter up to the water surface when they see me approach the tank. Three dispars, a carberryi, and a lyretail are either missing, or just perched on a rock, or wedged in a corner of the tank.
These "sick" fish look perfect, physically. Not a mark or blemish on them. Well fed, not at all skinny. The other fish, even the other anthias, pay them zero attention. They are from all levels in the hierarchy. The lyretail is the male, the dispars consist of the male, a medium female, and the lowest level female. The carberryi (only one in the tank) is larger than all but the lyretail. A couple things you do notice about them... their eyes don't move around very much, like healthy anthias. They just have this glassy stare (I know it sounds weird, but that's the impression I get). If you try to catch them, they will move, but only after you are practically already touching them, and even then it's just a short move to a new perch. Nothing like the darting of a healthy anthias ducking for cover. They will not eat.
Fast forward several weeks... and this is the first time this has happened for me. Two of the dispars and the carberryi start swimming around a bit. They sort of go for food...but they often miss it. Like they are drunk. They sometimes swim into rocks or other objects. After several more weeks they begin to eat well, and after a few months have made a full recovery. The lyretail and the third dispar just continued to perch, for weeks and weeks, until they were skinny enough/weak enough to simply catch with a net. The entire time, they never, ever had a physical mark on them, and strangely were never ever bothered by any of the other anthias.
This is not the first time this has happened to anthias in my tank, and a friend of mine has also seen this happen in his tank.
So... told you this would sound weird
