Corys losing barbels

[mambee]

I have a 90 gallon tank that has been running in its current configuration for over 5 years. It is filtered by an Eheim canister filter and I perform 35% water changes every week. It is very heavily planted with Java Fern, Anubias and Cryps. The substrate is very fine cichlid sand. (it used to be an African cichlid tank)

The water parameters are as follows:
pH 7.2
Nitrate <20
KH 80
GH 75

My problem is that my corys have lost all of there barbels. My original Adofoi corys were moved from a different tank because I thought that the substrate had caused the barbel loss. However, on separate occasions, new corys have lost their barbels. I have corys that were in a different tank who are losing their barbels in less than a week.

What is going on? Nitrates are low because of the water changes and the plants. The Eheim keeps the water crystal clear and the filter has enough of a current to keep any waste off the bottom. My corys are very healthy besides the barbel loss. Some of my Adolfoi are probably 15 years old. There are no aggressive fish in the tank.

Mike

[MatsP]

The common reason for barbel loss is "wrong substrate". Corys are "filter feeders" - they use their barbels and the nose to sift/dig through the substrate to find little particles of food. As such, the substrate needs to be small-grained enough that the fish can easily dig through it, and not have sharp edges. Most of the gravel sold in shops for aquarium use is unsuitable for corys (and no, the shop usually don't tell you!).

Soft sand, such as playsand and pool filter sand is very suitable. I'm not sure what "Cichlid sand" means - probably some sort of coral sand, which comes in all sorts of sharpness from round to quite sharp.

--
Mats

[mambee]

The substrate is CaribSea Eco-Complete Cichlid Sand. The stuff is almost like powder and is supposed to be "soft belly safe".

[MatsP]

Then I'm afraid I'm not able to help.

However, how sure are you that your nitrate level is right? It's well established that nitrate tests stop working after some time - this has fooled a lot of people into thinking their nitrate level is really low, when in fact it's much higher (mine was over 100 ppm, when it showed about 5ppm - and yes, the tank was a bit overstocked and in desperate need of water change)

--
Mats

[mambee]

The nitrate reading seems reasonable due to the water changes and the plants. I have Java Fern running amok plus lots of floating plants. I have to thin out the plants every few months because the tank is overgrown.

[Richard B]

Even if sand is supposed to be suitable for sand dwelling substrate dwellers it may still not beb suitable for corys - the grains need to be rounded not angular - this needs checking with a magnifying glass - as stated earlier, most barbel los is due to inappropriate substarte

[Bas Pels]

Instead of looking through a magnigfying glass, I put a bit - say a liter - into a bucket, fill the bucket half with water, and stirr- for some 5 minutes with my hand

Good sand does not result in abrasionmarks on my nails. Bad sand does

Obviously, as this basically comes down to washing the sand, I normally know whether the sand is suitable after washing it

[bronzefry]

Another cause of barbel loss may be water quality, but you seem to have that under control...what other fish are in the tank? Could they be stressed or injured?
Amanda

[mambee]

The corys are in a very peaceful SA community tank with mostly small tetras. I also have glass catfish and a betta who are never nipped at.