[DanG]

So one of my C. sterbai has had a growth behind a pectoral fin for some time (weeks? months?). He shows no adverse effects that I can see, behavior seems normal. Another of the group had a similar growth on its caudal fin (absorbing it), but that fish is long gone. I had thought this was something like Lymphocystis, as a couple of cardinal tetras had small white growths that maybe seemed similar and appeared like nothing else. Then just easier today It happens that the Cory in question posed for me. Attached are a side view, and then a ventral view, something I have rarely been afforded. The side view shows what I have seen for a long time now, what appears to be a growth. When I see the ventral view, I wonder if it confirms my suspicion that this is a growth of some kind, perhaps some kind of tumor. It almost looks as it began internally and then "split" the "skin" of the corry. Looks awful, although this fish seems to be behaving "normally".

 

[DanG]

Hi Folks, I've been doing further research on this, because another of the same group of C. sterbai has almost exactly the same growth in the exact same spot, but smaller. Apparently there is a gland in this spot (and behind the dorsal fin) that secretes a fatty secretion and can look like this (either the secretion or a swelling of the gland) if the cory has food that is too fatty. I wonder if this is the case. It is just too much exactly alike on both fish to be coincidence. Alas, I already euthanized the guy above along with a cardinal tetra, because I was concerned that it was Dermocystidium. A UVS will be installed on the tank in a couple of days.

 

[ichthyogeek]

Hi Folks, I've been doing further research on this, because another of the same group of C. sterbai has almost exactly the same growth in the exact same spot, but smaller. Apparently there is a gland in this spot (and behind the dorsal fin) that secretes a fatty secretion and can look like this (either the secretion or a swelling of the gland) if the cory has food that is too fatty. I wonder if this is the case. It is just too much exactly alike on both fish to be coincidence. Alas, I already euthanized the guy above along with a cardinal tetra, because I was concerned that it was Dermocystidium. A UVS will be installed on the tank in a couple of days.

What are you feeding the corys? It's interesting that there's a gland there of all places. Link to the source material please?

 

[DanG]

I am feeding the Caries standard sinking wafers, right now Hikari brand (with images of Caries and a Clown Loach on the packaging). It is interesting that the other species of Caries (there are two other species) had not exhibited the growth. All the Caries have been in the tank for some years and have gotten quite large.

I first came across the info doing research and I saw references in various tropical fish forum discussions. I have now found this paper: https://www.biologie.hhu.de/fileadm...6_07_Kiehl-Rieger-Greven-GfI-Bd_5_111-115.pdf

It is interesting that Figure 2 in the paper shows the exact location of the growth on both C. sterbai in my tank. I have some doubts that a fatty diet is contributing to a lump like growth at the axillary gland. I wonder if there might be another contributing factor, like swelling due to stress of some kind. Even though this tank is long established and carefully maintained, I will re-check water parameters, etc. It may be that the C. sterbai are more sensitive to elevated levels of nitrogen than the other tank occupants (and I do dose Nitrogen along with other ferts). Just grasping at straws here, but doesn't hurt to check, and maintain good maintenance of course.