Chromis Scales/Flesh Rotting, Sores? CALLING ALL HANDS!!!

[rinercl]

Alright, this is actually the second time this has happened to the same Blue-Green Chromis. I am actually not sure how he survived the first time, but he made a full recovery.
It basically looks like someone took a grinder to the side of the fish. It has a huge pinkish/reddish sore on its side between the gill and tail about the size of a dime. When it happened the first time (about 4 or 5 months ago) I thought I had somehow smashed him with a rock or something. The scales are missing and the underlying tissue is exposed and kind of roughed up. Both the first time it happened and this time, it seems to have appeared overnight. It loooks awful. I will try to post a picture later tonight or tomorrow.
It is weird for a couple of reasons. One, it seems to appear so quickly and seems to do so much physical damage. Two, there aren't any even moderately aggressive fish in the aquarium. All very peaceful. And three, it isn't apparently very contagious because all of my fish are always all over each other, rubbing and touching - especially when I feed them.
As I said before, this is the second time it has happened to the same fish. It took quite a while for him to recover last time (like a couple of months), and he had almost fully recovered. I could tell him apart from the rest of the Chromises because he kind of had some darker scales in the area where it happened before.
Also, I think it is important to note that I have searched through some of the other posts in this forum and have found several other instances of this same thing happening to Chromises with no ideas of what is going on.
I will try to get some of my aquarium water quality specs tonight. I am planning on a water change and changing out the carbon tonight, as that seemed to help last time this happened.
I have a total of six Chromises, a small Yellow Tang, and a pair of small Percula Clowns in a 55 gallon FOWLR tank. It has been up and running well now for about 2 years. Finally (within the last month or two) got fed up with fighting algae and put in a bunch more snails and hermit crabs. All algea is gone and I now have some good corraline growth. Also, I might talk a good game, but I am fairly new to this trade and don't know a lot of the acronyms and shorthand, so please keep that in mind. About all I know is FOWLR, LFS, and QT. And speaking of that, of course I do not have a quarantine tank. That would make too much sense.
Thanks for your help and sorry for making my first post such a long one.
-Cliff

 

[rinercl]

Here are some pictures of the problem. I also noticed one of my other Chromises has a similar spot, although much smaller.
Attachment 201788
Attachment 201789
Attachment 201790

 

[nuro]

soemthign similiar happened to mine too, Mine healed up fine in about a two week frame, but the area was much smaller and didnt look as deep. I had chalked it up to agressive natyure of chromis's and it hasnt reappeared, but im very curious as to what it was.

 

[spanko]

Looks like physical damage, rubbed against something or some nasty in the tank grabbed it.

 

[beth]

Very likely harassment. Is there a chromis that is unaffected?

 

[rinercl]

I thought it might be physical damage as well, but I haven't moved anything around lately and I have been very careful to get only non-agressive species. Maybe I am being naive. I currently have six Chromises, a Yellow Tang, two Percula Clowns, a Bumblebee Goby, a Cleaner Shrimp, and a Pistol Shrimp. With the exception of the Yellow Tang, the Chromis that is hurt is the biggest fish in the tank and one of the most agressive- although I have hardly ever seen any of them chasing or picking on one another.
I did notice this morning that one of the other Chromises (the smallest one) also has a similar wound, although his is about 1/5 the size and located up close to his dorsal fin. The other four Chromises are without blemish and all of my other fish look and act very healthy.
As I said in my previous post, I have read about some other folks with similar problems and injuries with Chromises and other fish. I think I can nurse what I have back to health, but I would sure like to know what in the world is going on. My wife and I actually spend quite a bit of time staring at the tank and observing the fish (we don't have internet or cable TV at home - and yes I know that is weird). We have never observed any real agressive behavior. My two Percula clowns were babies when I purchased them about two years ago, and I think they are starting to try and establish dominance between each other (as they are fighting amongst themselves quite a bit now), but I have never seen them going after any of my other fish.

 

[beth]

You need to spend some time observing your tank, from a distance, to see if aggression is going on. I think it is.
There is no such thing as fish that are non-aggressive, in fact, the clowns, chromis, and tang are certainly aggressive fish. They aren't predatory sharks, but they are territorial.