Help! Third Cory Death!

[NewFeesh]

Size of tank: 10 gallons
Fish: down to two peppered cories, originally five
Ammonia-0 ppm
Nitrite- 0 ppm
Nitrate- 30 ppm
pH- 8.5

I cycled my tank for two months fishlessly. The stats were excellent and stayed constant for a week, so I went ahead and got 5 peppered cories. Three days later, the first one turned red along his underbelly, chin, and gills. Then he started swimming erratically, as if he were having trouble steering. Then he stopped being able to swim to the top, and floated upside down at the bottom, every once in a while making desperate attempts to reach the surface, but always going still and sinking back down to the bottom before he made it. Then he floated at the top of the tank, barely moving. The odd thing is, when all three have died, none of them floated.

Also, none of them died within 36 hours of another. Like this is being propagated.

This is three of five. I don't know what to do or what the problem is. I just did ANOTHER water change last night (about 30%), but the third cory just died tonight.

The other two seem a little subdued but will chase each other around the tank sometimes and always seem eager for feedings.

Other stats:
Substrate: gravel/sand
Medium-planted tank
AquaClear 150 filter
Temp set at 76 F

Please help me and my cories!

 

[AstonN24vantage]

thats seems very awkward considering that you have no ammonia. are you using test strips? which test kit? keep doing water changes. im sure someone else will come along to help (i dont have a lot of expertise in this kinda stuff)

 

[fluffycabbage]

oh dear like the pp said, what test kit are you using? how long have you had them? are they young? it might be worth ringing the shop you bought them from and asking if theyve had any problems with their stock. i assume you are using dechlorinator when doing water changes?
the fact that the other two are possibly showing symptoms means it might be a good idea to get some medication in the tank - an all round antibacterial medication would be good, asap, and see how it goes.

 

[NewFeesh]

Thanks for the replies, guys.

I've got the API test kits. And as much as it's possible that I'm not shaking the bottles hard enough or whatnot beforehand, I took the first dead fish into the LFS along with a cup of my tank water, and THEY also tested it all for me and found it clean. I wish it WAS ammonia, almost, because then I could fix it.

Third fish is dead this morning, and one of my new fishes is now at stage 3 in the death steps: floating at the top, barely breathing.

This is just horrific.

 

[AstonN24vantage]

if i could guess i would say infection or parasite. if someone could confirm...

 

[NewFeesh]

Fourth one on his way out. Interesting though, this time the redness seems to be concentrated on his head (at the top), but of course I can only see the redness where he's got the "salt" patches in his "salt and pepper" design.

Also, his back fin is partially torn and individual fibers are fluttering forlornly.

I hate this sick waiting game. And what do I do if they ALL die? I can't just run out and buy another handful of cories and let them suffer the same fate again, can I? But if I go home for Christmas break and my tank doesn't have fish, I'm going to have to cycle the tank ALL OVER again when I come back.

*head in hands* Dead fish + exam week = bad bad bad bad

 

[Cary14]

I had this problem when i first started my current tank! two thirds of my fish died. My levels tested fine as well.
When i went to the shop however they said my ph was around 9 which is lethal over long periods. It was down to the gravel i was using, it was a limestone base and was raising the levels of the ph! so i changed the gravel to natural gravel and then they were fine!

Though the redness sounds like bacterial infection. But im no where near an expert!

 

[AstonN24vantage]

1 word for you. euthanize.

 

[NewFeesh]

It's just the last little guy left. But he's not showing any symptoms yet. I--er--really shouldn't do anything drastic to him unless he starts going red and bobbing around like an unbalanced balloon, right?

 

[fluffycabbage]

Have you given them any medication yet?

 

[NewFeesh]

Mystery solved. Apparently it's been my pH the whole time--I'm a little concerned that LFS didn't call me on that the first time I brought in a water sample . . . Anyways. Huge water change and "pH down," and I'm on my way to being able to keep LIVE fish!

 

[AstonN24vantage]

fail.

 

[Rynofasho]

8.5 is pretty high, yes, however you will quickly learn from someone more knowledgeable than me that 'pH Down' is not the long term answer.

There is dissolved mineral content in water that acts as a buffer against pH changes. That being said, you can put in pH down, however this will not work long term and your pH will again rise and you'll suffer the same fate. Some permanent alternatives to lowering your pH include adding bogwood to your tank (it possesses acidic quality to bring the pH down), so peat moss to your filter, or to use Reverse Osmosis water.

What sort of substrate are you using in the tank? As someone (I think) mentioned above, certain types of stones and gravel can raise your waters pH.

To test if they will, you can pour some vinegar on the stones and if it fizzes, it will raise your tank pH.

 

[Rynofasho]

And one thing that I forgot -- do you use aquarium salt? Corys are highly sensitive to it and you shouldn't be using it if you have them.