Dechlorinator deaths/sickness--advice needed.

[Bobrummel]

I am distraught because I had a massive die off. I made layer upon layer of mistakes, but here is my story.

I did a 50% water change. Nothing special, except that I threw out my old filter media after transitioning with my new media for a month. I also added back my charcoal media since it wouldn't fit when I had two sponges in place. Then, I left for a long weekend....

When I came back, I didn't "notice" anything amiss, but I can confess that I didn't look closely. Then, the next day, I came down with stomach virus and didn't pay ANY attention to anything. The next day, I looked at my tank and realized that all but 4 of my fish had died or were in the last stages of life. In the end, I lost 6 lemon tetras, 2 cardinals, 1 rummy nose, 3 random tetras, and my albino bristle nose. All of these survived my fish in cycling a year ago, so they were the best of the best.

The only thing that I can think of, besides the semi new filter, is that I may have forgotten the Prime, my Prime had gotten old since the last time I used it, or I overfilled my water and lost oxygen in my water. When I saw my dead fish, I did a 50% water change and added double dose of prime(I always add double dose, a whole cap for a 29 gallon tank).

The next day, I did another 50% change with a new bottle of Prime. I currently only have 3 remaining fish-1 Cardinal, 1 random tetra, and a Bolivian ram. They seem like they are all swimming ok, but they are not eating.

What should I do to try to help them! Is another water change in order? More Prime? Just wait it out? These fish usually go after the food, and the only one that is remotely interested is my ram. Also, I don't know if I still have any beneficial bacteria, but I don't want to lose them if I don't have enough fish to support their bio requirements. I want more fish, but I don't want to over stress the last survivors. So, I don't know if I should wait to get the new fish. So many questions...Please help!!

29 gallon community tank with 70 aqua clear HOB
Ammonia 0
Nitrite 0
Nitrate 40(before first post mortum water change)

 

[jessipanda]

If you had the new filter media in there for a month before removing the old media, and you aren't getting any ammonia or nitrite readings, then you should have plenty of bb in the new filter media. So it's unlikely that was the cause.

If you did a water change with tap water without adding the prime right before leaving, and didn't test the water within a week afterwards, it's possible that the amount of chlorine and chloramines in the tap water could have caused an issue in your tank, but was converted and/or fully dissipated by the time you got around to testing. This could easily cause a large die-off if the amount is significant enough. Have you tested your tap water for these or even ammonia itself? How large was that water change prior to your weekend getaway?

As for the remaining fish and their loss of appetite, 40 nitrates is high, but not extremely high. It's possible they were really stressed from the events that took place, and your back-to-back water changes may have further stressed them. However, I wouldn't worry about lack of appetite until it has been over a week or two. Fish can easily go a couple weeks without food. Hold off on feeding for a couple days to prevent adding any unnecessary waste to the water. Then, try feeding them a blanched piece of spinach or zucchini. Leave it for an hour or two, then remove it. Hopefully they'll pick at it. Both have a lot of good nutrients and can help improve their appetites.

I wouldn't add any new fish to this tank for awhile. I know you're worried about them not having big enough schools, but new fish should be quarantined for at least 3-4 weeks anyways, and you should give these guys some time to recover from the ordeal.

Good luck, and I hope your remaining fish survive and improve.

 

[Bobrummel]

Thanks

Thanks for the information! While I never wanted this to happen and feel horrible for my fish, I did learn a valuable lesson and hope not to have a repeat performance!

I did Check my tap water a year ago but don't remember all the specific numbers.

I will wait a while before getting new fish so that I can hope that my current trio can de-stress from their ordeal.

Will I need to ramp up my fish load slowly again since my benificial bacteria will not be used to handling 20 fish any more? I don't want to face an ammonia/nitrite/nitrate spike when I get my new fish.

 

[Barliman]

Will I need to ramp up my fish load slowly again since my benificial bacteria will not be used to handling 20 fish any more? I don't want to face an ammonia/nitrite/nitrate spike when I get my new fish.

I would wait for your current fish to de-stress and then add new fish slowly, allowing your bio-filter time to adjust.

And my sympathies. While I've never suffered a near wipeout, I did come home to find several of my brand new neons dead. Never fun.

 

[Matt68005]

Jessie about summed it up. Cycling or re-cycling (no pun intended) the tank is more important at this point than any med...