Cory barbel problems

[MSmith]

I've noticed that two of my five cories have what appears to be the begining of barbel damage. It's still slight, but I'm wondering what I should do about it. My gravel is not ideal for cories--it's not super rough, but it would prefer it be more rounded. If I were starting the tank again, I'd use sand. The cories have been in the tank since December. I check their barbel's regularly and it's only in the last few days that I've seen damage.

My nitrates have been higher than I like for the last couple of weeks--getting up to around 40ppm (ammonia & nitrites 0) right before water changes. I did a 50% change today (following my regular weekly 25% change on Wednesday) and did a thorough vacuuming of the cories favorite side of the tank. I pulled up the plastic plants, move the decorations and everything. When I moved the plants all kind of junk was stirred up. I think it may be dying algae. It definetely smelled like decaying plant matter and all the plants in the tank are healthy. I went through the standard new tank/newbie overfeeding algae bloom. In the last 1-2 months I've added a few low light plants (java fern, anubias) and cut back on light and feeding and I've noticed the algae going away. I think that may be why my nitrates have gone up.

So my questions are:
1) Could the fact that the cories are rooting around in all this decaying stuff be responsible for the barbel problems?
2) Do I need to treat them with antibiotics or will they heal on their own if I can get rid of the underlying cause?
3) If I have to I will change out my substrate, but it's not something I really want to do. Do I have time to see if better vacuuming and lower nitrates will reverse the problem (changing gravel if it doesn't)? Or will they worsen quickly if I don't change the substrate?

Tank info:
20 gallon high
Penguin 125 w/biowheel

0 ammonia, 0 nitrites
Nitrates were 40ppm on Wednesday--since then a 25% and a 50% water change have been done & I'm not sure of the exact value now

6 zebra danios
6 glowlight tetras
5 cories (trilineatus)
1 female betta
1 tiny snail (came in on a plant)

Thanks

[Hound]

I'm thinking your nitrate problem was due to decaying plant matter. I don't think that is why your cories show barbel damage though. If they are scraping up their barbels on your gravel bed you will probably have to do something about it. On a 20g tank I think you could probably do a gravel change in 2 stages. That is maybe do the left half one week and the right half the following week. Now if the barbel damage is due to something like bacterial infection then the gravel change won't help the damage. I've been thinking of changing some of my gravel over to sand as I'm getting it planted, but my corys don't show any barbel damage so I'm not really sure if I want to do the work.

[MSmith]

Thanks for the answer. I don't think I phrased my first question well. I pulled an all-nighter working on my qualifying exam so I'm a little fuzzy.

My thought with the decaying matter is that it would be a source of a lot of bacteria. So, maybe these two got a small scratch on one of the barbels and then because of all the decaying stuff then got an infection.

It just seems odd to me that I've seen absolutely no damage on any of them in 4 months and then 2 of them show damage at almost exactly the same time. 1 of them shows slight damage on one barbel, the other one has some damage on two of them.

I'm seriously considering just changing the substrate. I have another 20 gallon that I'm in the process of setting up as a heavily planted ram/cardinal tank. I could pull the plants and substrate out of that and fill it with sand. (It doesn't have fish yet.) I could then just move all the decorations and filter over to the new tank and use what is my current community tank for the rams and the cardinals.

[Hound]

I'd love a ram and cardinal set up, but why not have a few cories in that as well? Anyways I see what your saying. It might be that the corys have been scratching their barbels all along and you just couldn't tell. Then with the decaying plant matter and resulting bacteria they got infected this time. Again just shots in the dark really. If it is an infection I'm sorry, but I don't know what you could use on a cory without causing it more damage.

[MSmith]

I know I can't use regular medicine, but is melafix safe for use with cories? How about medicated food? I don't know where to get it, but I've heard it mentioned before. Would that be a possibility?

I've thought about putting cories in with the rams/cardinals, but I'm worried that if I manage to get a breeding pair of rams they might make life difficult for the cories.

[Hound]

Sorry I haven't medicated corys so I don't know what you can give them.

If you had a single pair of rams in a 20g tank I believe there would be enough room for 3 or 4 panda corys. I think they'd get the idea to stay away from an angry ram and so long as you have cover for them they should be fairly safe.

[johnnyxxl]

I am not sure about medicating the cory cats but if you do you could actually just clean the sand put the tank set up from one to the other without actually having to cycle the new tank

I would take a stocking and put a bunch of gravel in it and seed the sand with that and put all your water and fish etc in the one tank while you change your gravel to sand or whatever you want to do with it.