Never seen anything like this! Cory Death Help!

[GodFan]

Ok I have never seen anything like this and am begining to think I need to tear down 2 tanks and bleach everything and start fresh! Yes it is that bad!
I bought 12 pygmy cories for a 20 tall tank. They hid all the time but none died or seemed unhealthy. I decided to take them to my LFS since I doint like fish that always hide. Well my mom needed some for her 57 column (another story altogether!) so I figured it couldnt hurt. I threw them in (probably shoulda acclimated them but I never do acclimate fish from one tank to another) they seemed alright. Bets guess is about a month later I did a gravel vac for the first time (please dont hate i know it was stupid. I was more worried about cloudy water and figured between the cories and mollies the bottom would be pretty clean) well then I also added gravel. I tried not to hit any fish wilst I poured it in but it was probabaly stessful. Anyway immediatly after the cories seemed unhealthy. No explaination. Then they started dieing. The day after the first wave of deaths I decided to remove them to my 5 gallon to see if I could save some. In the sand I could see their behaviour better. Some of them seemed to struggle to stay upright. They would swim and lean heavily to one side. Well I had one death and wrote it off that I was simply to late. Then my brother comes downstairs and says one is bleeding?! I go look and sure enough there is a bright red spot (quiet large as well) on the side of one of them near the gills. I didnt do anything (what do you do?) and in a few hours I found it dead. There seemed to be blood on the edges of its pectoral fins and around the area that I saw blood originally.

Now I do not have a test kit (I keep tabs on ,my tanks pretty well) and their was only one other case of unhealthyness that I have seen in the 57 column. The oto that was in their (It was the oldest oto I had. It had lived through some beginner mistakes and such) had started floating. I thought he was dead. Nut he wasnt. Under his belly his underside was swollen and black. Swollen to the point that his scales were sticking out. He couldnt seem to stop floating and the guy at6 petsmart said it sounded like dropsy. I euthanized him.
So was this all because of my stupid mistakes or is something much worse going on? Please help!
Thanks and God bless!

 

[LyndaB]

Is it possible that they got nailed with the gravel when you put it into the tank?

They are very sensitive but I've never heard of the symptoms you're mentioning.

 

[GodFan]

It could have happened accidentaly but I wouldnt think this severe.... I put them in a cup for transport they coudnt of stabbed each other could they? Or at least the one that bled?

 

[BarleyBear]

You said you added gravel. Did it completely cover the old gravel? It is possible you put your tank back into a cycle if the new gravel completely or even mostly capped the old gravel. The good bacteria could have died off.

I only know this because I was considering putting a layer of sand over my existing gravel. I researched it first, though, and that was the big warning--capping off your established substrate. If I do it at all, now, I'll have to add the sand in gradually in small spots at a time.

That would be my guess as to what happened.

Also, I've read corries can be pretty sensitive to the tank bottom. They scavenge for leftover food and such, but regular fish waste still accumulates, so it's good to keep it vacuumed. I say this knowing that I need to do that to mine, soon. My current vacuum is too big to do the job, though, so I'm waiting on the smaller one designed especially for the Fluval.

Mabye it was a combination of stirring the bottom up and then capping the substrate off. Lots of toxins got mixed into the water, and then the bio-filter was sealed off preventing the bacteria from being able to break down the bad stuff.

 

[GodFan]

You said you added gravel. Did it completely cover the old gravel? It is possible you put your tank back into a cycle if the new gravel completely or even mostly capped the old gravel. The good bacteria could have died off.

I only know this because I was considering putting a layer of sand over my existing gravel. I researched it first, though, and that was the big warning--capping off your established substrate. If I do it at all, now, I'll have to add the sand in gradually in small spots at a time.

That would be my guess as to what happened.

Also, I've read corries can be pretty sensitive to the tank bottom. They scavenge for leftover food and such, but regular fish waste still accumulates, so it's good to keep it vacuumed. I say this knowing that I need to do that to mine, soon. My current vacuum is too big to do the job, though, so I'm waiting on the smaller one designed especially for the Fluval.

Mabye it was a combination of stirring the bottom up and then capping the substrate off. Lots of toxins got mixed into the water, and then the bio-filter was sealed off preventing the bacteria from being able to break down the bad stuff.

Well everybody has told me bb is in the filter so I didnt think that would be an issue. Ill be honest I messed up with the 57 gallon. I tried to do a fish in cycle and didnt do it right. I knew what to do but didnt do it. But I think they were added after the cycle was finished....

 

[LyndaB]

I threw them in (probably shoulda acclimated them but I never do acclimate fish from one tank to another) they seemed alright. Bets guess is about a month later I did a gravel vac for the first time (please dont hate i know it was stupid.

Aha! I missed this the first time around, I have trouble grasping everything in chunky paragraphs.

I do believe that whatever was stirred up in that substrate is most likely the cause of what's happening with them now. They cannot handle changes in water parameters well anyway and between not acclimating between tanks (although if mom's tank is in your house, probably close enough in params) and the long overdue gravel vac, they reached their limit. Sorry.....

 

[GodFan]

Yea my fault. The parameters are similar. Only difference is hardness. My fault. Live and learn.