Hole in fin - fin rot?

[Anthony]

I have a 2" C. Fowleri in a 35G tank with 4 other juvenile cories (skunks, similis) and 4 juvenile chain loaches. This Fowleri has been with me for 6 weeks now.

This afternoon, I've spotted a small hole (about 1-2 mm) in the center of the caudal fin. In 6 hours time, that hole has extended to the edge of the fin.

I've just added Interpet #8 Ant fungus and fin rot.

My question is whether this typical of fin rot?
(a) where it starts (hole)
(b) the speed it eats up the fin?

I did notice ever since it was bought that the area where the fin rot started was just a tad more whitish/opague in color.

Thanks.

ps. The other cories are fine. The tank is filtered by a 2026 and has sand bottom with a single large drift wood. No water parameters as I keep to the regiment of proper amount of feeding and change of water.

[Coryman]

First a question, did the hole in the dorsal fin gave a white edge to it?

Many people keep Cory's andLoaches together and in my opinion this is not a good idea, I too kept Chain Loaches with Cory's up until I spotted them taking pieces out of the Cory's fins. This may be the root of your problem.

Ian

[Anthony]

Coryman

The hole has no white edge to it. The missing part of the fin which is in the shape of a test tube has no white edge to it. I thought it is kind of "clean" for a fin rot case.

Your feedback on chain loaches is useful. I had thought of it before seeing the way loaches eat and punching little dents in the sand. I have not really seen the loach pecking on the fins but have on few occasions seen them "bump" into the larger cory.

[Anthony]

Michelle,

Thanks for the description.
I've noted the description as well as referenfce to the white edges.

I did a 60% water change before adding the Interpet #8.
The state of the fin now (after 14 hours) is the same as of last nite.
So, it could be fin rot or it could be the chain loaches as Coryman had suggested.

The shape of the missing part of the fin and no white edges may point more to the loaches.

[Anthony]

After further close observation, the chain loaches are indeed going after the cory (tail, underside, pectoral). Not sure when this habit started, they were fine during in the quarantine tank (or maybe I was looking hard enough).

Have removed them. Maybe they will go into my planted tank with cardinals and an angel fish or should they really be on their own?

Thanks.

[Anthony]

My last update:

I did put the chain loaches into my planted tank.... and they turn terrorists (!)

In particular, they like to hunt down the rummy nose tetras, but leave the koi angel, cardinals and golden algae eater alone (for now). Aren't they suppose to be nice little fellas?