I Need Help With White Mouths On Corys

About 6 weeks ago, I noticed what I thought was white fungus on two of my nine false juliI corydoras. One was on the mouth, and the other on the "saddle" near the dorsal fin. All Corys were acting normal and eating, but I quarantined the two and treated with Fungus Cure. Nothing changed, and as I did more reading on this forum, I began to suspect Columnaris. Not being able to get Kanaplex in my town, I ordered it but treated with Furan II in the meantime. When the Kanaplex arrived, I noticed that one more Cory in the 46-gallon display tank had the white mouth, and yet another Cory died overnight. When I examined her out of the tank, she had white lesions on her side and on her underside (wish I had snapped a photo!), she had a very hard off-white growth that looked like <1 millimeter diameter tubing coiled tightly like a rectangular pinwheel on her belly.

Feeling more certain this might be Columnaris, I moved the two from QT back to the display tank and treated the whole tank with Kanaplex (full course of 3 doses over 6 days). No change at all. The white areas on the dead Cory were definitely not fuzzy like fungus, but more lesion-like.

The two Platies and one Molly are unaffected as are 5 of the other Corys. I snapped a photo of the white mouth on one and the saddle white lesion on another (it's the smaller Cory in front) and the lesion is smaller than it started out, but you can see that the dorsal fin is only partly there.)

I don't know what else to do and would appreciate suggestions. The Corys are still acting normal and eating, but the lesions must be uncomfortable, and the affected mouths no longer have barbels. My water parameters are consistent with what they have always been. My water here is hard, and I have added crushed coral to try and improve buffer. I still use Wonder Shells.

Ammonia: 0

Nitrite: 0

Nitrate: 5-10

GH: 300

Cl: 0

KH: 20

pH: 7.2-7.4

I feed Omega One color flakes to the livebearers, and feed frozen Emerald Green, Mysis, and Brine shrimp to everyone, and also Omega One Shrimp Pellets and Veggie Rounds. I do 50% water changes, vacuuming the gravel once a week, so my nitrates are rarely above 10.

I would certainly appreciate advice/help with diagnosis from the Forum!

 

Could be the substrate is culprit.

 

What substrate would you suggest? Online discussions usually come back to some type of sand or very smooth pebble-type gravel (but then there is the warning that food mustn't fall into the cracks in-between pebbles, which of course it will). I have a "sand box" for them and direct some of the frozen food and pellets/wafers to that sand box, but some definitely goes into the gravel. I've had corys for 2 1/2 years, and this is the first time I've had the white lesions or barbel losses. The only change in the last 6-8 months has been that I've been feeding less due to having only a few livebearers left (and not replacing due to an upcoming move), so maybe they are having to root around more.

 

I would suggest switching to full sand especially if they have to forage around more. The gravel looks sharp in the picture and they might be getting cuts and then an infection.

 

Could you place a full tank pic.
I don't think the substrate itself causes the damage but food that might get out of reach in it. Or do you only feed on the sand?

 

Thank you for replies, CloudTheFluffy and DoubleDutch. The photo is over a year old, but the set up is still the same. I do put some of the frozen and dry food in the sand box which is most frequented by the smaller Corys but had also been using a pipette to blow a bit of frozen food over the area where the larger ones usually hang out.

I purchased 60 lbs of Caribsea Super Naturals Aquarium Sand and last night, very carefully changed out about a third of the gravel for the sand in the area where they do most of their hanging out and feeding. I will give them a day or two to adjust before changing out another third as I sure don't want to stress them any more than I have to. I'm leaving their "furniture" and plants intact except for the area I'm changing out, to give them plenty of cover. I am now feeding only on the sand so am hoping that they can start healing.

I will keep you posted on progress.

 

Fingers crossed. The substrate doesn't look that bad btw. Expected it to be a thicker layer. Will you treat with an antibacterial med ?

 

Yes, I have treated with Kanaplex a couple of times since the full rounds given earlier, just to head infection off and am keeping a close eye as well as keeping the water as pristine as possible. I have a couple of the larger Corys that are still cautious about the new "floor", but most of them are enjoying it and sucking the food up.

 

Quick update - I completed the last substrate changeout from gravel to sand tonight, in combination with a 50% water change which is typical due to livebearer bio-load. I'm anxious to be able to vacuum the first third but didn't want to disrupt the part of the aquarium that they were feeling safe in. I removed the sandbox since it's not necessary anymore, and administered what I hope is the last Kanaplex dose. For the first time, three hours after the changeout (and turning aquarium lights off), almost all the Corys are hanging around in the center front part of the aquarium where the sandbox used to be. I'm keeping fingers crossed that the really clean water and all sand will speed healing of the skin scrapes - assuming that is what they are. I'll keep you posted but am hopeful we're heading towards a better place! I'll include a photo when I have the lights back on.

 

The Cory's at feeding time with their new "flooring". They are acting normally, eating, and seem to have started healing a bit.