Mystery deaths suck

[Masha]

I'm not really looking for answers as I think this is one of those "could have been anything" situations -- I'm just feeling a bit gutted and have lost a lot of confidence in my ability.

My tank has been up for about 3 months - cycled, all going very well.
But suddenly my 3 peppered corys all started looking poorly (sitting on the bottom) and within a week 2 of them have died and the last one is missing presumed dead.

All the other fish are fine as far as I can tell, but they are tough fish (black widow tetras, bronze corys, silvertip tetras). The corys were the most sensitive fish I had, and my favourites too

I tested the water - ammonia 0, nitrites 0, nitrates never above 10.

As soon as I noticed the corys were not doing well I did large (60%) daily waterchanges which did seem to help at first, as they started swimming and eating again for a bit - but in the end they died all the same.

All I can think is that I accidentally got something in the water that harmed them so much that even the water changes could not save them. I can't think what though as I'm very careful. One thing I did do is to take my anubias and java fern out of the tank and sponge them down with a dilute solution of hydrogen peroxide to get rid of some algae.

I usually rinse my hands, but possibly I put my hands in the tank with something on them that got in the water? We don't use sprays in our house, and we don't smoke so I don't think it could be anything airborne.

I feed only every second day, but I put down pellets for the bottom feeders so I'm sure they were getting enough food.

I do 50% water changes once a week, very careful about dechlorinating etc. Tank is a 90 litre with 8 black widow tetra, 5 silvertip tetra, 4 bronze corys, 1 zebra danio and 1 java loach. Lots of live plants.

Anyway, I wish I did not care so much - and I can't help worrying there's something going on that might harm my other fish.

Thanks for reading

 

[Tommy10]

I'm sorry for your loss

 

[threnjen]

I am so, so sorry.

I can empathize with how you must be feeling right now. My tank is recovering from a recent illness and for me it was the cories also, AND like you they are my absolute favorites. It has been absolutely heart wrenching. I still continue to lose a cory every few days although they are now in a tank alone. I feel like I'm just waiting for them to all die off.
I've felt similar discouragement about my aquarium keeping skills.
My cories of which I have lost 7 of 9 were even punctatus cories which are very closely related to and look much like peppered cories.

So I just want to say, I've totally been there.

Were there any physical abnormalities on the cories, either before or after they died?

I really, really, really don't want to worry you further but unexplained deaths, especially amongst a single species, can be columnaris (which is what infected my tank). I've also read several things suggesting that cories are particularly susceptible to it. I don't want to freak you out or send you running to buy meds but just keep it in the back of your mind while you monitor the other inhabitants closely.
There is too much info out there about columnaris and much of it is WRONG so if you even start to suspect it PM me and I'll send you my best curated links.
Suffice it to say I and some other forum friends have been researching it... a lot.

 

[Masha]

Thanks for the kind words, Tommy and Threnjen.

Threnjen - I've been following your story too - so much more wrenching than mine! I'm sorry to hear that the deaths are still going on in your case.

I had a pretty close look at the little guys who died and cant see anything unusual about them. I don't see anything that looks like columnaris, thank heaven. That is one nasty disease.

 

[flitabout]

I had something very similar happen to me. Right after I complete my cycle I got 8 cardinal tetras, 3 swordtails, and 2 platys. For the first month they all seemed very well and then my male sword started flashing and was dead in hours. Then my girls dropped babies and several days after themselves died. I thought that maybe it was just the swords until the same thing started to happen to my platys. I lost few if any of the fry and none of the cardinals. My water parameters were all perfect I was checking them twice a day. Ammo and nitrite 0 and nitrate between 10-20. I ended up not getting any new fish for a really long time after I lost the last adult but I still have no idea what caused the deaths.

 

[Masha]

That must have been horrible, Flitabout.

 

[flitabout]

It really sucked, and I can't say it was a learning experience, because I didn't learn anything other than blaming myself because I didn't know what happened or how to stop it from continuing.
Masha you are doing everything right. Just give is sometime and let it play out. Most of all don't beat yourself up.

 

[Masha]

It really sucked, and I can't say it was a learning experience, because I didn't learn anything other than blaming myself because I didn't know what happened or how to stop it from continuing.
Masha you are doing everything right. Just give is sometime and let it play out. Most of all don't beat yourself up.

That's just how I feel too. Thanks Flitabout - I needed to hear that.