How common IS this disease? And no way to prevent it other than not add angels? Terrible! Is this an outbreak that's happening? Do we need to have to worry about it now more than ever?
Ugh... I had a nice lengthy response to this typed out and my internet decided to blink off at that very second and I lost it. So I'll try again and hope I didn't forget anything I was trying to say, lol.
I'm not sure how common it is now, but it is definitely something that merits some research. If I remember correctly it first surfaced in the 80s and wiped out quite a few angelfish hatcheries. Breeders lost their entire stock.
Personally I have come across the disease twice (plus a reinfection that was my mistake most likely) in about two years. Both times my entire stock of angels was killed, and both times the fish came from the same store (Come to think of it, I bought a few juvies from the same store maybe 8 months ago and they all died in qt, I had forgotten about that. Not sure if it was this disease or just general bad health this time though). The reinfection took all of a group of juvies I bought from an aquabid seller, although I think that was because I didn't disinfect the tank or wait long enough before reintroducing angels. At that point I wasn't aware of how long it can stay in a tank, and I got new angels maybe two months after the others had died. These fish were healthy for a few months then withered away, and one by one they had trouble swimming and staying upright and died. I'm guessing the disease was still in my tank and waited until something caused their immune systems to weaken. If not that, they could have come in infected, but the seller I got them from had very good reviews as far as the health of their angels.
As far as avoiding it in the future (of course after the possible carriers have been removed from your tank and the tank has been disinfected) I would highly recommend avoiding pet store angels and instead buy directly from hobbyist breeders with a good reputation for healthy fish. Fish with wild blood may be even better if you can find some, as this seems to be a disease of captive bred angels (there have been lots of problems with angels lately due to bad breeding - fish are weaker and don't have the nice form they did years ago, just ask andy or bob). Chain stores and local fish stores usually get their fish from large scale hatcheries, and the more fish kept in a system the bigger the chance is of them having been exposed to disease. Buying from small scale breeders does reduce that risk somewhat. On top of buying from better sources, you want to be sure to qt all new fish for at least 3-4 weeks, maybe longer. If you notice any fish looking less than 100% healthy, extend the qt until they do. This will greatly reduce the risk of adding anything nasty into your main tank.
It really really sucks having a disease wipe out a tank full of fish. I've been there, and its really depressing. Just don't give up!
don't give up! You're too good for that! I'm really afraid of this virus. No signs or symptoms? I'm never adding new angels. How long cannot lie dormant? Meaning, could fish I've had 2 months have it?
