PlanetCatfish.com

I have a 6" Black Ghost Knife in my tank for about a year.

I have noticed over the same period that all of my cories are missing their whiskers. It may be my imagination, but it seems like the tubercules on my bushynose cats are shorter than they used to be.

My nitrates are very high, and I have been addressing that by doing large water changes twice per week. I also plan on swapping out my flourite for sand.

Has anyone had any problems keeping a BGK with catfish?

Mike

I never had any problems keeping a BGK with catfish. I suspect the problems you are seeing are due to the nitrates.

I have had my BGK (named SpaceGhost) for several years and "he" has been housed with several different species of catfish including corys. No problems yet. I definitely agree with Silurus...your nitrates are the culprit. You may want to go to your LFS and buy a Nitra-Zorb nitrate pillow that helps absorb the nitrates. They come in different sizes depending on the size of your tank. Good Luck.

Nitrates, thats the problem, you need to get them down and keep them down, I would suggest daily 20% water changes and decrease the amount of food you are giving the fish. A shallow sand substrate is a good move, but I would also look at your filtration system, it would appear not to be coping very well.

Ian

Hello Mike,
You seem to have a dual problem here. Most important is to get rid of the nitrates, to make your cories happier. There have been several solutions given yet to do so.
Please bear in mind however, that black ghosts aren't particularly fond of water changes. So if the ghost is going to behave in an unusual manner, you know where the problem may come from.
I would also like to confirm the meanings of earlier reactions, that black ghost are harmless to almost any fish: I have 6 with e.g. Corydoras robinaea, Tatia perugiae, Tatia spec. guiana and Microglanis ihringi. All rather small fish and unharmed by the ghosts, of which the largest is about 25 cm (10 inches).
Good luck in solving your problem.

Well, I switched to a sand substrate over the weekend (what a hassle) and I have been doing partial water changes (30-35%) twice per week.

At some point in the near future, I plan on setting up another tank and will transfer the cories and maybe some other fish.

I run 2 Eheim 2028 canister filters on my 150 gallon tank. Great filters, but I get the feeling that they stockpile nitrates. I tried trailing the roots of philodendron plants in my tank to absorb some nitrates, but my Uarus considered them a snack.

I have an ecclectic community tank which works, with zero aggression:

Catfish:
9 cories (mostly Adolfoi)
Synodonitis Brichardi
Dwarf Bumblebee Catfish

Plecs:
Gold Nugget
Bushynose (2)
Vampire
Clown
Spotted (unknown)

Cichlids:
Blockhead Cichlid
Uarus (2)
Festivum
Geophagus Surinamsis

Other:
Assorted Rainbowfish (6)
Congo Tetras (5)
Siamese Algae Eaters (2)
Flying Fox (2)
Black Ghost Knife

And my personal favorites:
Clown Loaches (4)

Mike

Most filters do not remove nitrates, or at least not a lot of it. The "denitrification process" assumes anaerob conditions, i.e. no oxygen in the water. This is the opposite of what you want for the fish, and it's also the opposite of what you want for removing the more harmfull ammonia and nitrite.

Plants will do a better job, but if you have a well-stocked tank, there's only one way to get rid of Nitrates, and that is to change water.

Also, make sure that the new water is as nitrate free as possible, of course. Here in england, the nitrate level is allowed up to 50 ppm, which means that it's "bad" for many of the sensitive fish. So test the tap-water before you put it in the tank. If it's high, you can get a filter to remove Nitrate in the water, or you can start looking at Reverse Osmosis Units, which will remove all sorts of things, hardness and nitrates amongst those.

So make sure you change that water. And of course, bear in mind that the source of the nitrates is the food that comes into the tank, so less food makes less nitrates. This of course is particularly important if there's food left uneaten, as it's not even giving any useful nutrition to the fish...

--
Mats