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Cardinal Tetra difficulties

3354 Views 7 Replies 5 Participants Last post by  sphack
Last Sunday, we picked up 10 cardinal tetras from a LFS of varying sizes (.75"-1.5") to add to our planted tank. We acclimated them for 3 hours in the tank slowly adding water to the bag floating in the tank.

On Monday, I got another shipment of plants and finished planting tank. At this point, I could only count 9 tetras. I found the 10th in the canister mechanical filter.

Off an on, some of the tetras looked disoriented. One morning one of the fish was nose down against a plant on the substrate. Occasionally, when one of the fish one swim, it would twist and end up side down. As the day would progress, they would look better. Last night, my wife stated that all the fish look good. (I'm out of town and returning tonight)

Today, my wife found another dead fish (and removed it). One more fish is unaccounted for. Testing the water, there is now a trace of ammonia (0.25 ppm) and the nitrates are higher than I've ever read at around 40 ppm. Until this point, the plants have been keeping the nitrate level at 10 ppm even with fert dosing.

Here's the numbers:
75g tank
fish: 4 bn plecos, 9 rasboras, 6 panda corys, [STRIKE]10 9[/STRIKE] 8 cardinal tetras.
plants: a lot with cambomba and parrot feather growing nicely, sag and cyprus grass, others (dhg, lugwidia, and many others) just starting out
nh3*/4: 0.25
no2: 0
no3: ~40 ppm
ph: low - 6.3 in the morning before turning on the CO2. pH meter turns CO2 off at 5.6
kH: 4-5 degrees
gH: 3 degrees
temp: 79 (though there was a spike to 82 on Tuesday afternoon)
ferts: ppm-pro 7ml, excel 7ml last dosed on Tuesday

My wife is going to be changing 20gal of the water this morning. Any other suggestions? We really want a school of cardinals, but so far, they're not liking the tank.

I don't have a quarantine tank but do have a 20L planted tank that is going through a fish-less cycle that is destined to be a shrimp tank. That guy is heavily planted and sitting at ~74 degrees.
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It looks like your aquarium is kind of new, so that could be part of the problem. Even a small ammonia spike could be a problem for Cardinals. Having said that, Cardinals can be a bit tricky. Loosing a certain percentage, when stocking, isn't necessarily reflective of doing anything wrong. Once they get established, you shouldn't have a problem with them. The dead Cardinals themselves could be responsible for the ammonia, and nitrate spikes. Do your water change, and do more if you need to keep your nitrates down below 20ppm or so.
Could've been a bad batch from the store - you acclimated them very carefully! Sometimes you do everything right, but there's still problems and's part of the game, in my experience!

Or, maybe when you added the rest of the plants, the gravel bed and beneficial bacteria in it was disturbed, causing the spike in your parameters. A water change will definitely not hurt at all.

I have 4 cardinals now who have survived 3 moves and 2 bouts of ich. Whenever I add more, the noobs die, but the 4 are tough as nails. Keep trying, once you get a good group, they'll stick around :)
I agree with with above. Cardinals can be tricky. Alot of it can come down to if you have a good supplier or not. In the past, there was only one lfs that I could get Cardinals from and have at least 85% survive. Some are imported others are tank raised. Imported ones have lower survival rates due to stress of shipping.

As far as your plants, I don't think they are heavy on the consumption of toxins as others. Not all plants consume aquatic waste the same. Perhaps the addition of the Cardinals pushed the plants to a limit. Although Cards are small, they still have to be accounted for.
New tank and NO2 and NH4 issues, NO3 plays no role.
Even at 100ppm plus.

Water changes are good, Zeolite etc anything to remove the NH4/NO2 mostly.
Once the filter is mature.........then there are few issues.

Shrimp often have the same issues.
Just to follow up after a few weeks... While I'm down to three cardinals, I finally figured out I believe the main problem: the fish were not getting enough O2. None of the fish showed the classic gasping for air on the surface, but did show other symptoms. Sluggishness, decreased eating, the pandas were hiding, occasionally a rasbora would be disoriented in the morning, higher activity after water changes... After putting an air stone in i saw immediate (30 minutes) change - ALL the fish just came alive! I could measure the Co2 being aired out for in that time the ph rose a full half point.

I'm still running co2 but at the higher pH. Don't know how much my algae has affected the plant growth and pearling and hence the oxygen.

Anyway after adding the air stone two days ago everybody is doing well and eating and swimming. :)

I have an co2 titration test coming on Thursday so I can measure the pH in ppm. The drop checker never showed yellow; it was always a solid green. Don't know if something is off with the dc or not. Caulk it up as another learning experience. Many others gauge their co2 by their fish behavior. Now that I know how my fish behave I can confidently see the the signs. And only at the expense of some cardinals and a pleco. Thankfully everybody else survived.
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Good to hear you may have your issue solved. Do you have your co2 on a timer or it runs 24/7. Remember that when plants aren't making food, they consume O2. At this point everything in the tank is competing for O2.
I picked up a dozen more cardinals yesterday. So far only one fatality. I have been running my airstone initially. Unfortunately I'm now running into filter problems :(. Assuming my pump keeps running until I get a backup installed things are looking good.
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