Cory die off

[mroth_3]

I have a 10 gallon with 7 young peacock gudgeons and about 7 small cory cats and a few shrimp that came in on the plants. I came home and the cories are all motionless or laying in akward positions while the gudgeons and shrimp seem to be fine. Some of the cories are laying on their side and back and one was for sure dead.

I did a water change last night 50%. Tank paramaters are No3= 5ppm Ammonia=0 No2=0. I just did another water change but this time with water from my 65 in the off chance that something in the water is affecting them. Cories have always been the most resilient fish for me. Anyone ever had them all die off but the rest of the fish fine?

 

[jpappy789]

How long have you had the corys? Anything added or subtracted from the tank recently? What did you do during your latest maintenance period before the die off?

 

[mroth_3]

They've been in there for 3 months. I just did the same 40-50% water change I always do. I use prime as a conditioner. Nothing added since they were put in the tank for grow out. They have been on flake for the last 3 weeks to a month and are all about 6-8 months old.

 

[PapaMann]

Could the peacocks have something to do with it? Hard to believe all the corys would be attacked at the same time.

 

[cicrush13]

Gudgeons wouldn't cause this. There is something else going on here.

Are they eating? Any physical symptoms?

 

[OliviaBolivia]

I had 5 die off once.......I think it was a combination of things (5 weeks neglect of tank with no water changes......and being bullied by yo-yo loaches, and therefore missing out on food).

But also worthy of note is temperature.....I learnt that 24 C is just about as much as corys can handle in the long term, any warmer and their longevity definitely decreases. I was keeping my tank at 25-26C at the time, and had kept them in that for about 7 months.

I now have a separate tank which I keep at 24C, and my two little schools of julii and panda corys seem to be very happy.

I don't, however, have any suggestions for you.....my five died off one after the other, a few days apart. They didn't all go belly up at the same time? Have you notched up the temperature of late? I can't think of anything that effects corys and nothing else, apart from temp.....

 

[AngelFishRock]

Temperature and salt, cories are not very salt tolerant.

 

[allaboutfish]

are you sure corys dont like higher temps? i keep my tank at 80 with no problems.

 

[jpappy789]

I kept C. aeneus at 80-82F when I had blue rams. It will largely depend on the species but I would think most are fine in the 77-79F region even...

 

[allaboutfish]

are julii and peppered ok at 80? (im not meaning to hijack the thread)