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i was looking closely at my cories last night and noticed that their barbals are very short, look stunted.
haven't really noticed this before so don't know if always been like that or not.

i've got 9
had 5 juilli for over a year now
2 juilli for around 4 months
and 2 sterbai for a week.
the substrate is small river gravel and sand. no sharpe objects.
i feed them every night when the lights go out, with algae waffers, and cory pellets. they also clean up after the other fish have been feed.
Could they have been damages by other fish?

www.blooming-brilliant.co.uk

Nope, and the problem isn't your substrate, either. In fact, substrate doesn't seem to ever damage cory barbels. That is just a myth.

Your problem is most probably high nitrates. Cories are somewhat sensitive to nitrates, and their barbels often get infected (and subsequently shorten) when high nitrate levels are present. Your best bet is to just start doing extra water changes and vacuum the gravel more often. Once you pick up on that, your nitrate levels will drop, and your cories' barbels will regrow soon afterwards.

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

I too once thought substrate had nothing to do with it. However, I think substrate, combined with a possible protozoan infection that may have them flicking/scratching on it, has something to do with it.

But Sirbooks is right to want to check nitrates. That would be the first thing to rule out. The second is diet. Cories need high protein food that is varied and fresh. If you buy something like Wardley's Shrimp Pellets, throw away what is unused after 60 days or it loses much nutrient. That is true of any fish food and a good reason to buy the smallest package, as opposed to the bargain big one.

I have habrosus cories - a version of pygmies. One I've had almost 2 years and she grew barbels in my tank. I added 5 a year later and one or two of the were flicking intermittently (turning sideways and scratching on the gravel). Several had few or no barbels. Within a few months, my first habrosus was the same and by this time, one had the erosion going deep into his face. He was flicking moreso. There was no visible signs of parasites.

I have sinced move them from my tank which has slightly sharp flourite and into a bare bottom 10 gallon. I'm seeing it get no worse, and one continues to scratch occassionally, so I'm going to have to treat with something more drastic like formalin. I think if the flicking hadn't taken place, and if there wasn't sharper gravel, they may not have gotten microscopic knicks leading to infection.

Look to see if yours flick as they are wandering around. Look to see if it is happening throughout the day. Cories will occassionally get a piece of food stuck in a gill as they sift and they will body slam sideways to dislodge it. Don't confuse it with that. It is just an annoying rubbing motion on the gravel.

Infection is always a concern and potential. I would do a very good gravel vac first, after checking nitrate level (bag some water for fish store if you don't have a nitrate tester). Check your ammonia and nitrite to make sure they are zero. If you have no live plants, no UGF filter, and have a pretty strong filter that is running at least 100-150 gph, then go for a deep gravel vac. In my 20 long, I remove everything I can including my non-rooted live plants, and then I use the tiniest of gravel vacs to go slowly, methodically back and forth, to the glass. I hold it in place a second or two so that it collects the gunk. Bacteria can collect in compacted pockets and make its way up into the water column. You'll be surprised what comes up where decorations or fake plants were.

Always replace water with same temp water and stop when you get to a max of 30%. You can always do more a day or two later.

Then, dose the tank with a combination of Melafix and Pimafix. If there is a mild infection, this can help and is relatively benign with respect to bacterial filter. Just pull activated carbon. However, if you have an older filter with no separate sponge or biomedia, try to just dump the carbon out of the cartridge, or cut it out, so you can save the good bacteria.

Sirbooks, while your hypothesis about excess nitrates being a contributory factor in Corydoras barbel erosion is probably grounded in sound thinking, substrate can have an effect. Derek Lambourne reported this in his Corydoras book. He bred C. habrosus in an aquarium containing fine sand, and experienced a horrific level of attrition among his fry beginning with severe barbel loss. Later spawns in an aquarium with a rounded gravel substrate suffered no similar losses.

However, even in an aquarium with a tame 'Cory friendly' substrate, chances are that excess nitrates could precipitate barbel erosion. I think more research needs to be conducted to isolate the various contributing factors. Cory_Di suffered barbel loss in her adult habrosus, yet I think you would agree that her maintenance régime would be an effective leveller of nitrates: she devotes a lot of TLC to her Corys. A sharp substrate AND excess nitrates would, in my view, be the worst possible combination. But, until someone actually conducts some experiments under controlled conditions, and establishes whether or not barbel erosion can take place in some species at least even in water with low nitrate levels if the substrate is sharp or otherwise irritant, I suspect that the question will remain open. Cory_Di suspected her substrate because of her maintenance régime, and when I told her about Lambourne's documented experiences, this heightened her suspicions.

It would also be instructive to discover if any pathogenic organisms appeared in any biopsy samples. This, however, is a matter for someone with decent laboratory facilities to determine.


Panda Catfish fan and keeper/breeder since Christmas 2002

Substrate indeed does corrode barbels.

high nitrates are a cause too, but not always. My 55g has very high nitrates, and my corys barbels are fine.

Usually it has to do with infection.

I've been struggling with cory barbel erosion for some time now on my pandas.

The strange thing is they lose them ever so slowly irrespective of what I do.

I do regular weekly water changes of 50% or so and the nitrates used to be zero, and in fact I have to dose nitrates to fix my BGA problem.

Now, the substrate is silica sand and isn't very sharp, but they keep losing barbels.

I've tried dosing the tank to get rid of parasites and any sort of infection, but to no avail.

The next step for me is to soften the water with a mix of R/O and tap water as I beleive the high gH has something to do with it.

How about flicking? Do you see them flick periodically during the day when foraging?

I have a belief that flicking, even periodically, against anything that is remotely sharp, causes microscopic abrasions, which then get infected.

It's baffling.

It is, they used to flick a lot more before I started to dose KN03, some people beleive that flicking is caused by having no nitrates present.


They still occasionally flick but not really any more.