Nitrite levels

[Fred T. Washington]

Hello everybody,
I have a question about the nitrite levels in my aquarium. Shouldn't there be some nitrite showing up in my tests? My last test results for my 37 gallon tank were as follows;
Ammonia 0ppm
Nitrate 20ppm
Nitrite 0ppm
Hardness 150ppm
Chlorine 0ppm
Alkalinity 40ppm
pH 7
Temp 78F
My aquarium has been set up for about four months and I have yet to record any nitrite in my tank. The ammonia has never gone above .25ppm and the nitrate has never been above 20ppm.
If my biological filter is working properly, shouldn't nitrite show up at some point?
This last test was the lowest alkalinity I've encountered yet. I plan on addressing that and the water hardness this week.
I have this nagging suspicion that something is not right with my tank. My school of neon tetras (18) are acting normally but my corydoras paleatus hide almost all the time. If I do catch a glimpse of them, they immediately dash for cover. They have hiding spots and a sand bottom but still don't seen at ease. I also have one panda cory (unsure of scientific name) that seems completely happy. The panda is normally the only cat I see. I have also had three of the corydoras paleatus die (five remain) over the last month.
Please share whatever wisdom you have about what I am doing wrong or right or completely missing.
Thanks

[andywoolloo]

first in the tank cycle comes ammonia, for some weeks, then nitrites start to come into play, then you have some ammonia and nitrites till the nitrites become big enough to take care of the ammonia, then the nitrates come into play a few weeks later.

A cycled tank will have no Ammonia and no nitrites for a week, to be safe, and just test for nitrates.

Maybe you missed the NI part or it was a slight. Zero ammonia and zero nitrites and 20 ppm NA sounds likes you are cycled.

Cories , imho, are susceptible to high NAs, I try to keep mine at 5ppm in all my tanks. They do not like the NA's to be too high. In my experience. I have plants in all my tanks and i do 50% water change every week.

what are you feeding the cories? do they have places to hide? How many are there? they like to be in shoals, and liek to have hidey holes and caves. Most of my cories are out and about in their group all the time.

[MatsP]

Just to make it clear: If your biological filter is working correctly, you should NOT see nitrite. Sure, during the cycling process you may find that the nitrite level rises above zero whilst the bacteria builds up in the tank, but if you have properly working set of bacteria in the filter, nitrite should ALWAYS be zero.

Is 18 neon tetras and a few corys doesn't sound like a high load in the tank, so you may not have had much nitrite level in the first place - it may have gone unnoticed during your cycling. And I suspect you didn't put ALL of those fishes in at once, so the bioload will have been lower than that to begin with.

And as stated in the other post, corys do not like very bright tanks, so a lot of plants and hidey holes is the best way to make sure they are frequently visible - it sounds contradictive, but if you think of it as agorophobia (fear of open spaces), you'd realize that a cory that has somewhere nearby to hide will be much happier than one that is in the middle of an open stretch of sand.

Paleatus corys are cooler water species (so are panda corys), and should be kept in the lower 70's range (unfortunately, that'll be no good for your neons, so a compromise closer to the mid-70's would probably be the best solution).

--
Mats

[Fred T. Washington]

Thanks for the info.
Let me know if I have this right: It starts with ammonia, then nitrite is next? and lastly nitrate? I thought it was Amm. trate, then trite.
I have lowered the temp to 76F
I feed tetra color flakes and one Hikari sinking wafer once daily. There is a fair amount of hiding places in artificial plants, enough to make it impossible to see all six cories as once.
My current water change schedule is 10% weekly. I will bump that to 25%.
Any additional thoughts always welcome.

[andywoolloo]

ammonia is first then nitrIte then lastly nitrAte.. Then when you test for ammonia and nitrite and they are both zero for a week, with some nitrAtes tested you can consider yourself cycled. I do 50% water change every week on my tanks. My nitrAtes stay at 5 ppm.

it's 37 gals yours, and what all is in there? stock wise?

How many cories if that's all that's in there?

When I had 12 all together I fed them a cube of whatever defrosted frozen once a day, if I wasn't feeding defrosted frozen I'd give them sinking items like shrimp pellets and carnivore pellets or NLS granules. Mine never liked the hikari sinking tropicals. And the amount of sinking pellets was usually around 6 for the twelve of them. Or a few smidges of the NLS granules. They went absolutely bonkers for defrosted tubifex or bloodworms or shrimp tho.

As far as decoration mine really enjoyed driftwood and live plants and caves. They were out and about all the time, not scared or timid at all. Cause I think I had lots of hiding areas for them all over. It really is true the more cover they have the more they come out. Altho cories are pretty outgoing catfish anyways.

[Fred T. Washington]

Thanks for the clarification on the cycle.
I have 18 neon tetras that range from 3/4" to 1". The cat population is 5 corydoras paleatus and one panda cory. That is all.
The tank is a 37 gallon extra deep.
I occasionally feed them frozen tubifex worms. They don't strike me as going "bonkers" for it. It all gets eaten, but they react the same for their normal feeding.
Here is a pic of my setup. The white arrow shows my panda cory (as usual, the only one visible). The peppered corys are in there usual spot, hiding behind the striped rock at the base of the plants.
The flash makes the tank appear quite a bit brighter than it really is.

[L number Banana]

Hi, I'm certainly no expert but the regulars may be able to clarify for both of us:

Is there enough oxygen in a tank this deep for the corys? If not would that make them a little skittish or shy? I was once told that it should be very deep for that reason but I can't remember if the source was a good one or not

[MatsP]

The oxygen levels at depth depends a lot on the circulation in the tank. If there is an air-stone in the tank, the water will be rotated up/down as well as around the tank by the filter.

But corys are pretty OK with lower oxygen levels, so I'm not sure it's much of a problem, actually. Fry of corys require relatively low water levels, but once adult they have been known to live at 3m depth in rivers, which is deeper than most of our tanks would normally be.

--
Mats

[Chrysichthys]

If oxygen is too low, you can tell tell because they will frequently dash up to swallow air (although it is normal for them to do this once in a while).

[Fred T. Washington]

I don't think my tank has any oxygen problems. My filter discharge creates a decent current and I also have a surface skimmer on the filter intake. None of the neons act oxygen starved.

I was advised that my cats are acting like they have a bacterial infection and was encouraged to treat them with Maracyn-Two. Mere hours after beginning this treatment one of the corydoras paleatus was foraging out in the open. This was something I hadn't witnesses in a long time.

I will keep posting updates as warranted on this thread.

[andywoolloo]

how were they behaving besides hiding? did they look different? can you post any pictures?

[Fred T. Washington]

There are lots of artificial plants that they like to his beneath. There is an especially dense section towards the back of the tank that is their preferred "safe spot".

So far today I have yet to witnessed the foraging I saw yesterday. They just hide. Their breathing does not seem to me to be unusual, typical to what they do when they sit on the bottom at the pet store. Movement sends them dashing for cover if they happen to be out of their safe spot.

They have no swelling or unusual coloration that I can see. This is the best pic I could get before my camera battery crapped out on me.

Like I said, you can't give me grief for not providing them ample cover!