Sterbia Cory Health floating

[PamC]

I have a few new sterbia cories, meaning they arrived Friday night. I lost two Friday night I expected that. But tonight I am seeing one with some odd behavior and wonder if the same did not happen to the other two, just unobserved.

The cory seems to have lost its ability to keep itself one the bottom of the tank. It will struggle to stay down and lose that battle sometimes no struggle just a slow float to the top. Once at the top it will try to wedge itself in the water sprite and then about 30 secs later it will swim back to the bottom. Right now it is laying in the water sprite breathing very heavy, very labored. Can not see any redness on the gills, maybe the angle I am looking at him. What could be the trouble here?

As it is the quarantine tank, 13 gallon has been running for one year
1/3 water change daily, water conditioned with Prime and aerated for 24hrs
82 degrees
No Ammonia
No Nitrites
No Nitrates
pH is 7.5
GH 6
KH 6
Has driftwood, algae moss ball and water sprite and 3m color quartz S grade sand
Running an Ehiem Ecco rated for 30 gallons
plus one air stone
Other quarantine members sterbias (5) and German Blue rams (5) plus one BN pleco about 2 inches (tank keeper)

None of the other fish seem to be affected at the moment, however I am concerned that I will be losing the other cories just one at a time. What is going on?

[Cory_lover]

uhhh has your tank and filter been cycled yet? I know it's a quarantine tank, but it should still be cycled. Plus, 1/3 water change daily seems weird/unnecessary. Also, are you sure amm/nit/nitrates are ALL zero?

[PamC]

Yes the tank has been cycled, it started out over a year, as my first tank. I did the water tests as I observed the cory and the floating - swim issue. The tank, when not used as quarantine, has a BN Pleco as the only inhabitant.

The water from the tap
Faucet readings
PH 7.6 (alkaline)
GH 6 or 107.4 (neutral)
KH 6 or 107.4 (neutral)
Ammonia 1ppm
Nitrite 0
Nitrate 0

Yes the one third water change is weird, but the tank went from holding one BN pleco to holding the one BN pleco plus 12 rams and 8 corries in one day. Major bio load change from what I understand.
So the next day I found two cories floating and I pulled 7 of the rams and placed them in a different tank. So the tank went from one fish to 21 fish to 13 fish.
I understand corries and rams are sensitive to water chemistry, thus I do a partial water change daily, rather be stable then permit too much bio load crash the tank. Not sure if that is even possible with my GH & KH readings (still learning about that part).

[Cory_lover]

ah yeah that seems like quite an increase in bioload. If i'm not mistaken, if ammonia's already at 1ppm, it will likely to stay at this level for a couple of days, then changing to nitrite, which is also unpleasant for the fish..the only thing I guess you can do now is to keep doing the daily water change, without touching the biofilter, and add fresh water with Prime. Additionally, you can also buy this product called Purigen (from seachem) which uses a special absorbent material to absorb any nitrogenous waste, hence acting as an extra weapon against nitrogen poisoning. I used both prime and purigen when i experienced a similar thing, and although there were fatalities then, the use of both has prevented any such things from happening again thus far.

[PamC]

Got a photo of the cory resting on the water sprite, the cory is actually a bit above the water. I can see a little redness this time does that mean something in particular. Is this an irritation from anything in particular?

Just weird I have read a few other posts about similar behavior but they did not seem to have any floating plants or observe their fish resting on the plants before attempting to reach the bottom again. Not sure if the plant is helpful, but one one seemed to have their cory recover either and that creates concern for the rest of the corries and tank mates.

Thanks for the Purigen suggestion. The ammonia seems to disappear after the use of Prime and the 24 hours of aeration prior to placing in the tank. I have the water sprite and moss ball to help with the nitrates once the bio load goes through the cycle. Not a planted tank, just a few floating plants that are supposed to make use of the nitrates from the water column. I will read up on Purigen to see if that is something to add to the quarantine tank at a later date.

[Timberwolf]

I had similar issues with my corydoras aeneas last week. I lost 2 of my 5 and and had another sick one recover. In the end, it seems that I got some fish who were not in the best of shape. The advise of Cory_Lover and also MatsP really helped me get it sorted out.

Good luck in working out your problems. I am new to keeping cories, but it only took about a day and a half to become completely hooked.

In addition to the products that Cory_lover reccommended, I have had terrific luck with another a bacterial additive called SafeStart.

[MatsP]

Yes, I agree with Cory_lover, your tank is essentially cycling - your ammonia and nitrite levels are going up because your biological filtration isn't up to the new bioload. Big water changes is the only solution - however, it seems like your tap-water has a fairly high level of ammonia in itself, so it's not really great. You may want to consider using some other source of water - e.g. bottled spring-water. I'd try to avoid using RO/Demineralized/distilled water, however.

--
Mats

[PamC]

Thank you for all the input.
I understand why one would think the tank is not cycled from the numbers posted. I went to retest this morning and discovered (as I suspected) I had incorrectly posted the test results. I always need my eyes glasses for small print.

Tap
Ammonia 0ppm (not seeing the chart clearly I assumed the progression started with 1 and was in whole numbers rather then the .25ppm)(should have just posted No Ammonia as I did with the tank posting)
Nitrite 0 ppm
Nitrate 0 ppm

Tank
Ammonia 0ppm (not seeing the chart clearly I assumed the progression started with 1 and was in whole numbers rather then the .25ppm)
Nitrite 0 ppm
Nitrate 20- 40 ppm (may have tested to soon after the water change, last night)

The cory is still alive this morning, still coming up to the water sprite to rest at the surface. So could be a weaker fish is reacting to the high nitrates. Alright, I know what I need to do now.
MatsP I will be asking more about your comment on the RO DI, however I need to read some more on the subject.
Again thanks to all, for your comments that caused me retest and think a bit more about what is going on.
Cheers

[MatsP]

In short: Using RO/DI water increases the risk of a pH crash - that's not good for you, the fish or the good bacteria that live in the tank.

However, if you have no measurable level of ammonia in the tap-water, then go ahead and use tap-water, it should be safe and appropriate.

20-40 ppm nitrate in the tank water with 30% water change each day seems a bit strange - I can think of many things to explain it, but none that makes much sense. The most likely being that your tap-water contains more nitrate than you have listed in your test...

Either way, 20-40 ppm nitrate on it's own shouldn't be a problem to most freshwater fish. There are some really sensitive fish that would balk at 20 ppm over a long period of time, but I doubt you have any of those species. Certainly, C. sterbai should be fine at 40 ppm without probem - I keep them in Surrey tap-water which runs about 35ppm out of the tap [1].

[1] Technically, it's waste-water from my RO system, so it has about 20% HIGHER nitrate than the tap-water, so it would be about 40 ppm rather than 35. Because my RO system produces a rather large amount of water per day, I get a lot of waste-water, so the 4 x 100 liter tanks that get the waste-water will have about 400% per week water change.

--
Mats