Big Fish Die Off

[LadyR]

Hey all, I've got a totally serious issue with my tanks and I have no idea what's going on. I've had almost half the fish die within the last 36hrs. They are fine and then within a couple of hours are dead. But the weird thing is their tails look like the skin is gone, the colors are gone and it's like you can see the structure but nothing else. This morning it was my betta George in his own tank. We got 6 new fish for the 26gal that has been running for 3 weeks. The water has been great, we used the Tetra Safe Start, had 6 zebra Danios and 2 plestcomus, 2 glow tetras in it, along with several varieties of real plants. ANd yes they were all awuatic ones. The plants are grwoing like gang busters and the fish were all doing fine. Then I think the temp got a little high (closer to 80 than 76) and we lost 2 zebras. But I kinda expected losing one or two. So things have been good. No ammonia or nitrites, nitrates below 30ppm. So we went to the LFS and got a couple different plants, a driftwood piece and 2 glow tetras ( we already had 2 to me they look more like hatchets but whatever, they are bright yellow) and 4 sunrise guppies. I planted the plants, soaked the driftwood in the tub with hot water for 2 hours, and I thought acclimated the fish. I added the fish and a little while later added the wood and everything seemed fine. This was Thurs night. Fri I got up and 2 guppies were dead, 1 seemed off, one that seemed off when we got it was dead too. The off one I moved into my betta tank thinking that maybe the filter wash was a little too much. By the time I got home from work he was dead too. Then 1 of the plesto's died after we had seen both of them out swimming around the wood. I checked water again and the Ph had dropped .2 from 2 days before. We have way hard water and there's not much to do about it. I had read the wood might help, and we need another decoration. So now this morning my betta is dead and he had been swimming around the last 24 hours. He's been way off for a couple months, but finally seemed to be better. He had even eaten yesterday! BUt today his tail colors are gone like the guppies. So what the heck is going on??? I'm going to do a 25% wc but that was the plan for today anyway. I just don't know what to do. Since the tank was so new we figured that it was essentially like a QT, but now I'm wondering. Help???? I've added a pic of the big tank. The water is slightly colored from the wood, but clear otherwise.

 

[skjl47]

Hello; Do not really have an answer, but can comment on a few things.
First, 80 degrees is not too high for most fish except cold water types like gold fish. The fish listed should handle it well, zebras for sure.
At three weeks your tank(s) may still not be cycled. There are several threads on cycling on this and other fish sites.
I lost track of all the fish and when they were added. It may be that in a tank not fully cycled that the fish numbers were increased a bit too soon and you had an ammonia spike. The pleco's are some what nasty fish in that they produce fairly large amounts of waste. (They will also get to be very large and even one will outgrow a 26 gallon tank.)
My approach to pH and hard water is to have fish that can handle whatever water I have. The pH is not a problem for many fish as long as it remains consistent over time.
I do not use wood in tanks so cannot comment from experience, but it is an easy thing to remove if you have doubts. I have read posts from others about the tannins in wood staining the water. I seem to recall that some soak wood for days to weeks to reduce the stain. I also recall posts saying that soaking wood in a bathtub can stain the tub.
Live plants are, in my opinion, good to have in a tank and should help with the nitrate/ nitrite part of tank cycling.
Good luck.

 

[LadyR]

Thanks. I'm just kinda at a loss with this one. I had figured out my error in changing the filter pad in the 5gal, and I was pretty sure that was why my betta was having a hard time. So haven't made those errors with the new big tank. I'm almost positive it was the guppies that must have had something. And then when I moved 1 to the 5gal tank, that's how my betta got it. ALthough he's been having a really hard time for several months, so it might not have been anything related to the guppy die off. ANd yeah I'm not sad the pleco died, bad choice, but still..... Just wish I knew if I needed to treat anything or not.

 

[skjl47]

Hello; When I come across an unknown situation like you have described I often leave thing to sit the way they are for a time.
Some weeks ago I bought several zebra danios and placed them in a quarantine tank (QT). It went well for a while, but around a week and a half they started to die one by one. The abdomens became slightly red and the fish were listless for a day or so before they died. By the time the episode was over all but two had died. I left those two in quarantine for over three weeks and eventually moved them into a nother tank. I have since had more new fish in the QT without incident and without trying any treatment on the tank.