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Why do my cories die ?

5.3K views 36 replies 19 participants last post by  aokashi  
#1 ·
Hi,

I'm very close to giving up on cories.
My 60g community tank has been established for several months, heavily planted, and all fishes are doing well... except for cories. I lose about 1 a week. It's usually very sudden, no warning signs, in the morning I will spot one with trouble swimming, and by the end of the day, he's dead. No wounds that I can see either. I've had cories from several different sources, and it's always the same thing.

Here are my water parameters I change 50% weekly):
pH = 6.5
TDS = 56
Ammonia = 0
Nitrites = 0
Nitrates = 40ppm (hard to get an exact reading with API's kit)
Temp = 77

The substrate is this one: http://www.aquariumplants.com/Freshw...trate_p/ss.htm
The grain sizes are pretty uniform, and about half to 1/3 the size of eco-complete.

Does anyone has had similar experience ? Any advice for keeping those guys ?
 
#5 ·
brainwave, they are young. On the other hand, I have 3 survivors (from an initial school of 15) that I have had for almost 2 years now.

The other fishes are green neons and ember tetras- the cories are the biggest fishes in there !

somewhatshocked, I don't have a GH/KH tester, but I live in NYC where the water is extremely soft. I don't run CO2, but maybe the large number of plants is enough to cause significant pH swings between night and day ?
 
#9 ·
don't have an answer but i have had the same issue, sterbi cories dying off in groups, preceded by crazy swimming. I assume it is some sort of swim bladder issue, maybe infection. but then i have no problem for months...
 
#10 ·
and i don't think it is the temp. i've kept mine (before any issues) at 84 with discus
 
#11 ·
ptr

The next time you order from Ken's, get some earthworm pellets or flake. My cories go crazy for them.

I wish I could help more but I also had a tank of young Bronze Cories that died off the same way and I haven't figured out why. The only thing different that I noticed was that they never seemed to eat as much or as actively as my other cories.
 
#13 ·
I have 29 gal planted tank with green and orange laser cories and probably vacuumed the substrate only once in 2 years. Never had any issues...

Edit: though, if moving/replanting plants with big roots might release the "crap" out of the substrate. I usually use vacuum to suck the dust right after taking out the plant.
 
#20 ·
hmm, I have a low tech tank with soil under the substrate.
I've had pygmius for 6 months and habrosus for 1 month. They are fine. I don't vacuum. I do have a canister filter rated for a much bigger tank.

I think the soil substrate tend to release ammonia which will harm the bottom dweller. A powerful filter and light substrate vacuum should work out.
 
#21 ·
Interesting thread. I have to admit cories are one fish type I have not been able to keep long term. I've tried to establish schools twice and I think I got maybe 3-4 months out of them. In the same tank are kuhli loaches, ottos, cardinals that I've had for years. I also live in NY and the water is very soft. I notice no sign of infection either as they just start to succumb.

Edit: I should also add that I'm pretty anal about my setups and do large regular water changes and gently sweep the bottom in unplanted areas.
 
#22 · (Edited)
#23 ·
I don't know; I'm not so sure about the water hardness part. I don't think NYC water hardness affects them that much. I've kept aeneus, panda, duplicareus, arcuatus, sterbai, pygmaeus, and metae each for several years now in NYC. The only cory death I've witnessed in these past few years was a single panda and arcuatus(which jumped out).

But to be fair, I've never kept C. julii before. If nothing is found out of the ordinary, I wouldn't go as far as giving up on cories entirely. Maybe just try out a different specie with a reputation of being hardy. They're great fish, especially when they shoal in mass.

Best wishes,
-Epi
 
#25 ·
ur nitrate reading just seem too high for the corys to handle it... i notice death when that level has been reach

IF you say it's not accurate...better get a really good reading from it.. buy a API master kit for accurate reading!

I have them in my tank with 10ppm to 20 ppm and still alive since... i have a one year old albino cory.

Also can you tell me what water condition have you been using and how long
 
#27 ·
I have the API master kit - but frankly, the color difference between 20, 40 and 80ppm is very subtle.

Betta Maniac, did you have them with soft water *and* lots of plants ? I am wondering of the low KH, combined with the plants, causes big pH variations at night when the plants produce CO2.
 
#28 ·
I have the API master kit - but frankly, the color difference between 20, 40 and 80ppm is very subtle.

Betta Maniac, did you have them with soft water *and* lots of plants ? I am wondering of the low KH, combined with the plants, causes big pH variations at night when the plants produce CO2.
still need some question answers