Tank Disaster, I'm killing fish and I don't know why!

[Snwbirdy]

So a week ago today I finished a fishless cycle on my tank (12 gallon) after a little over a month using ammonia. I did the 4ppm turnover test and it passed perfectly. For the rest of the week I kept dosing to 1ppm to keep everything alive and then did a big water change on friday to get nitrates down for fish on saturday.

On Saturday I added 4 little julii corys after doing a drip acclimation for about a half hour. All water tests came back 0 ammonia and nitrite and under 20ppm nitrate that day and Sunday. One of the little guys wasn't very lively from the start and this morning I found him dead . Another has an eye that is bulging which is freaking me out. Tested the water and found .5ppm ammonia, 0 nitrite and 10 ppm nitrate. I panicked and did a 30% water change then another after a few hrs with no lower levels of ammonia.

So now I am feeling like a terrible fish killer and watching my sick cory because I feel like he is going to die any minute. My ammonia is still too high but I don't know why. Help what have I done wrong??

 

[ptray1982]

You added too many fish for your bb colony to keep up with. It takes a little time for the colony to get established. In that small of a tank you added to much waste too fast. Use an ammonia remover (fish will make enough to keep the colony alive) and keep doing 25-50% water change daily and it should work itself out in about a week

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[venymae]

You added too many fish for your bb colony to keep up with. It takes a little time for the colony to get established. In that small of a tank you added to much waste too fast. Use an ammonia remover (fish will make enough to keep the colony alive) and keep doing 25-50% water change daily and it should work itself out in about a week

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I disagree. If you dosed 4ppm ammonia then a couple of little cory cats are not going to be enough to put you over your bb load amount. 4ppm of ammonia is a lot of fish! That being said I am surprised you read any amount of ammonia with that low of stocking level.

Potentially your fish could have been sick before you brought them home and the stress of moving (even if done properly) can sometimes just be too much or hasten the disease. Pop-eye is a symptom of disease learn more here Poor breeding can be a cause of fish dying for no reason. What is your pH level? That might have something to do with it, pH can sometimes go a little crazy during a fishless cycle, though a big WC should have helped that....just putting out ideas.

 

[Snwbirdy]

Thanks for the replies you guys. I do think that the stress of moving might have been the cause of the death, he just wasn't looking very good from the start. As far as PH goes i have a PH of 8.2 but so does my LFS. I tried not to over stock at first but I did think that after dosing 4ppm ammonia I might have a little more room. The only thing I can think of is I did maybe go a little gravel vac happy when I did the big water change due to algae build up during my cycle. Maybe I got rid of too much bacteria and messed it up?

 

[Sgtdap]

Almost all of the bb is in the filter so don't worry about that.

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[trennamw]

What are your pH and temperature?

 

[Coursair]

A 12g is really tiny for C julii IME.
They need at least a 20g Long for floor space for a group. They get over 2" as adults.

Pygmy species might be better. Also Cories enjoy live plants. Mine sit on them and play around them.

http://www.planetcatfish.com/common/species.php?species_id=378

I'm sorry yours got sick. Corydoras are great fish.

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[trennamw]

If you check the third page of my thread "Journal: Restarting fishless cycle ..." Threnjen posted some amazing info about how ammonia toxicity is often lower than we think and is based on temp and pH. You can check the chart but I think that situation isn't actually ammonia toxic. It's really worth a read I'm sorry I don't have the link handy.