PlanetCatfish.com

1. Water parameters
a) Temperature range - 76
b) pH - 7.5
c) GH - Unk
d) KH - Unk
e) TDS - 265
f) Ammonia 0, Nitrate 5.0, Nitrite 0
g) Water change frequency - Biweekly, 25%
h) "Routine" water treatments (e.g, chlorine/chloramine or ammonia neutralizers; pH or hardness adjustments, anti-stress chemicals, tank-cycling bacterial mixes).
- Dechlorinator
2. Tank set up
a) Size - 20g Long
b) Substrate - Play sand
c) Filtration - Fluval Aquaclear 30 (w/ 50 impeller)
d) Furnishings - Plastic Plants, Driftwood
e) Other tank mates - 5 neon tetras, 1 L104, 1 LDA068
f) How long has it been set-up? - 5 years
g) Food used and frequency - Tetra flakes, shrimp pellets, frozen blood worms
h) Recent changes in the tank which occurred shortly before the disease/problem appeared (if any; e.g., changes in water source or water treatment, changes in decorations or substrate, replacement or changes of hardware (filters, heaters, etc.), and additions or removals of live plants or live fish) - None

3. Symptoms / Problem description or history - I have 5 panda corydoras that have been in the tank for approximately 3-4 years. In August I was extremely busy with work and my tank husbandry suffered a bit. At the end of the month I noticed that all of the pandas had lost their barbels, and 1 of them looks like most of his mouth is gone. All are eating and appear otherwise healthy and unstressed.

4. Action taken (if any) - Increased frequency of water changes to weekly, seeing no improvement I pulled all the plastic plants and discovered a lot of detritus was clumped around the bases of them. Removed plants altogether to scrub and clean later (have a had a recurring issue with fibrous green algae) and yesterday I did a 60% water change. I didn't plan on taking that much water out at once but the rate that my siphon tube pulls is pretty fast and there was a lot of junk to vacuum up.

5. Medications used (if any) / changes in fish observed since treatment began (if any) - No change since lowered nitrate from 20ppm to 0-5ppm over the last month. Have not tried any meds yet.

This was the first freshwater tank I've setup with sand as a substrate. The two plecos make lots of poop and it has been a challenge to keep up with. I also added alot more plastic plants then I usually do since for a whlie the pandas were laying eggs and I was hoping the dense cover would allow any fry to survive. I'm at a loss as to what to do. I can't recall if it was playground sand or pool filter sand, but it was whichever one people said to use when I was researching it. It's very fine white sand and it doesn't feel sharp at all to my fingers. The depth of the sandbed is between 1-2" and when I do water changes I stick my fingers in it and usually some small bubbles pop up but I don't ever smell sulfur. Based on research all I can think of is that the sand is abrasive and has worn down the barbels, or that I wasn't doing an adaquate job cleaning up the detritus and it is what infected the barbels and caused them to erode. I'm half tempted to just pull the sand and put replace it with gravel. I thought corys preferred sand but I've never had this issue with them on gravel in the past.

Unrelated note but kind of cool: apparently the two plecos are 9 years old! viewtopic.php?t=33214 The tank has been up for 5 years at my current house but I moved it from my previous residence.

It's most likely to be a bad choice of sand, but poor water quality can cause this. Given the sand has not changed in years, I'd say it'd be the water...

Jools

And here we are replying 9 years later lol. Like Jools, especially given the age of the tank and past good health of the fishes, I would focus on the water rather than the substrate. Living conditions in all tanks degrade over time despite our weekly maintenance routine: the fish grow, larger fishes need more food, more food digested is harder on the filter, filters become less efficient over time, etc, etc. More frequent, larger water changes are a great first step to correcting those accumulated imbalances. However, if it were my tank, I would do a complete tear down to clean the substrate (using old tank water) and perform a full cleaning/ tune up of the filter.
-Shane

Definitely water changes. 25% every other week is too little. Try changing 50% weekly and see if you see some barbel regrowth. I am also wondering how often you vacuum the the tank.

My impression is your TDS are too high. Your TDS translate to a hardness of about 15 dg.

Thanks for the responses. I vacuum every time I do a water change but with the 2 clown plecos it sometimes seems like I could vacuum twice a day and not keep up. Regarding the TDS, I live in upstate NY and we do have pretty hard water here.

And, Shane, I think that might be a good idea. Maybe I'll move the fish to one of my QTs and pull and rinse the sand.

Just to add my 2c I think 2" of sand is way too deep for a small group of blunt-nosed Corys, I would reduce it to about 1/2". The bubbles popping up may well be nitrogen from de-nitrification due to anaerobic conditions and if the corys are digging in this they could be exposed to poor conditions in the deep layers of the substrate.

After removing excess sand, as well as more frequent water changes with regular vacuuming I would even suggest adding more inhabitants that will turn the sand over, be they other compatible fish or inverts (burrowing snails, mussels), or better yet more corys Bronze corys are particularly robust diggers.