Cory with Missing Fin and Cotton-ish Growth

[Kr_Treefrog2]

My tank is 120 gallons with six Agassizi cory catfish, one Banjo catfish, and seven Giant Danios. It's been set up for over two months now, is fully cycled, and I just added the Agassizi and Banjo two weeks ago. I had to go out of town for the weekend (no worries, they have an automatic fish feeder), so the last time I saw the fish was on Friday afternoon. When I came home today (Sunday) I saw that one of my cories had a white, cottony patch over its second dorsal fin. Upon closer examination, it looks like the poor thing's second dorsal fin is actually gone, as well as some of the skin around the area. I immediately moved it to the quarantine tank and medicated the water with Microbe-Lift Artemiss. It seems to be doing fine, no apparent changes in behavior, appetite, or clamping fins. I checked all the other fish and they seem fine and do not show any signs of infection or stress. I did a water check right after that with an API Master Test Kit as well as test strips and got the following:

Ammonia - >0.25 ppm
Nitrite - 0 ppm
Nitrate - 10 ppm
GH ~125 ppm
KH ~ 100 ppm
pH - 7.6

I've been doing 25% water changes weekly, and for the past month and a half I've been changing out the very hard and very alkaline tap water with pure RO water. The water finally got into reasonable levels a couple weeks ago, and that's when I started adding fish, but I'm still trying to bring the levels down to a pH of 7 and KH of 90 ppm. The tank is heated to a steady 78 degrees. I'm guessing the cotton fluff is a fungal infection that has set into the fin wound, but I'm stumped as to how it got torn off in the first place? I didn't think cories got aggressive in schools, the Giant Danios ignore the cories, and the Banjo cat just ignores everything. Any ideas on how this happened or what the cottony stuff is exactly?


Note: I keep getting an error message when I try to post a new thread that says I've exceeded the tag limit, but there's not even a box for tags on my posting screen. Any way to fix this?

 

[kashea]

There are a few thing that could have happened here. First off, do his other fins look okay? I've never had this happen to my cories, but some of my mollies have had an issue where they've gotten fin rot and then gotten fungus on the wound. Although, if it is fin rot, I doubt the whole fin would be clean off in just one weekend. If all your other fish are nice (and it sounds like they are) then the only other thing I can think of would be if your fish somehow got its fin stuck in the filter and that tore it off. It may be unlikely but I used to have a filter in one of my tanks that had such a strong current, it sucked my fish in multiple times. It may be best to try to get a second opinion on how the fin got torn off, but you should start medicating asap. I'd suggest using Melafix by API, it's really worked for me. Best of luck!

 

[Kr_Treefrog2]

Thank you for the response. I looked him over thoroughly yesterday and the rest of him is fine, just the one fin. I've been keeping a close eye on the other fish in the tank, and I haven't seen anything amiss. I started medicating the poor guy as soon as I moved him to the quarantine tank with medication I had on hand, but I have some Melafix on order as I've heard good things about it. I've dealt with fin rot before a few years ago, but this doesn't seem like fin rot. All his other fins are clear and intact, no milky white lining or frayed and split fins. As to the filters, they have a high capacity but large piping as well, so there isn't a strong pull at the intake. I've seen the cories hanging out right underneath it without being disturbed. This one has me well and truly stumped.

 

[Fishfur]

If you can get some Indian Almond leaves, they have natural antibacterial properties, as well as adding beneficial tannins and humic acids to the water. I used them to heal severe fin injuries on several Bettas, which I adopted because they were injured. Not a fungal specific, but does support the fish generally while it heals. One big leaf or two smaller ones.. leave it in the tank til it looks like a skeleton, then replace. You can also make tea from them. Use cold water, steep overnight until the water turns dark yellow. Use a cup or two with every water change.

It is too bad you can't use salt, but the catfish are pretty sensitive to it. It's a very useful treatment for both bacteria and fungi.

I might guess he got a spine caught, perhaps, struggled to get free, caught the fin under something or between two somethings ? Hard to say. Before I started using a prefilter on the uptake tube, I had a couple of big mystery snails die because they got their foot stuck in the bars of the Aqua Clear tube at the bottom. Wish I'd noticed they were stuck, but it is not unusual for them to stay in one place for some time, so by the time I realized they were stuck, they had drowned.

Sometimes fish can damage themselves in odd ways. I had one Betta that nearly put out an eye, and there was nothing, but nothing, in his tank he could have hit, rubbed or been struck by.