Deaths during water change!?

[Mmil9533]

Hi All,


Over the weekend, I was doing my usual weekly 75% pwc on my 55 gallon and I noticed 2 of my cardinal tetras were floating belly up! Everyone was fine previously and I tested my parameters before starting:
Ammonia 0
Nitrite 0
Nitrate 10
I netted them for a closer look and their coloring was still bright and completely normal. They weren't moving, so I touched them gently and they moved a bit, but stopped again. They died a few minutes later. I do move rocks and driftwood when I'm changing water, but I am very careful about knowing where the fish are so I don't accidentally harm them. Anyone know why this would happen so I can prevent it in the future? Thanks in advance and sorry for the novel!

 

[Bix22]

Is the water you are adding close to the same temp?
Also why do you do weekly 75 percent PWC, I am fairly new so I was wondering about that.

 

[Mmil9533]

Yes, I try to match the new water temperature as close as I can. I discovered the fish floating while I was still vacuuming the gravel, before I had put in any new water. I usually do a 75 % water change every week because my tank is stocked to capacity and I have a pleco who is messy, lol. Thanks for your input!! I just want to try and figure out what happened so it won't happen again

 

[Rodeo one]

I had 3 Tetras die in 5 min cuz I forgot I d put lotion on my arms that am.

 

[Mmil9533]

Oh no, that's awful! Sorry to hear that! I guess I never thought that something as simple as lotion could cause so much damage. I usually wash my hands with soap and water a few minutes before I do a water change. Could this have poisoned my fish? Its just so strange because this has never happened before and it happened so suddenly.

 

[f1shg33kz]

Soap is very toxic to fish. It breaks down their slime coat. I'm not sure if it would kill them that quickly though. I usually just rinse my hands if they are relatively clean already. If you want to use soap, rinse super well. Soap can leave a residue on your hands so I try to rinse extra good before diving in to my tank. It's also a good idea to wash your hands good once you are done working in your tanks. Fish tanks are loaded with bacteria.

 

[Taiken5968]

The 75% change could e stressing them out too much. I did a 50% change in a 10 gallon not too long ago. Shortly after the change I found that two fish had died. Both were very healthy. I had raised them from fry. One of them, a neon swordtail was about 6 months old.

 

[Taiken5968]

You may want to do 30% twice a week instead. What kind of conditioner do you use?

I hope that is the only reason they does and nothing serious. Sorry about the loss. I had to learn the hard way on some things.

 

[Jonnypro]

My tank is stocked to the max and I don't do that hefty of a water change. I have a great filter that helps with keeping my water clean. I wouldn't do 75% a week. I would do 35. As long as you have good circulating and plenty of oxygen in the water you should be fine. I have had my tank for almost 2 years with over 20+ fish with some Horny cray that keep multiplying and a turtle. I have only lost 2 fish since my tank had been fully established.

 

[f1shg33kz]

I don't think large water changes are an issue. Discus keepers routinely do 95% water changes and Discus are some very sensitive fish. I've been doing 50% or larger water changes for years without issues, I find that it helps with spawning in many species. If something induces spawning, I don't think that it is really all that stressful.

The OP said the fish died while the tank was still being vacuumed, It is far more likely the fish either had a pre-existing condition that was not externally detectable or some kind of contaminant got in to the water.

 

[Alyxx]

I don't think large water changes are an issue. Discus keepers routinely do 95% water changes and Discus are some very sensitive fish. I've been doing 50% or larger water changes for years without issues, I find that it helps with spawning in many species. If something induces spawning, I don't think that it is really all that stressful.

The OP said the fish died while the tank was still being vacuumed, It is far more likely the fish either had a pre-existing condition that was not externally detectable or some kind of contaminant got in to the water.

I agree, the culprit is probably a contaminant or something already wrong with the fish. Or maybe some sudden movement stressed them out bad enough to kill them. Or maybe it was just bad timing - they may have died at that very moment whether you had done a water change then or not.

I also agree that there is nothing wrong with large water changes. I do huge changes weekly on all of my freshwater tanks and have never had a problem. My 56 gets a nearly 90% change a week, simply because I feel like I am wasting prime if I don't change a lot of water since with the python style water changer I use I have to dose for the whole tank anyway. So I change almost the whole water volume. Keeps my water pristine and no fish have ever died because I did a big water change.

 

[Mmil9533]

Thanks for all the responses! I also use Prime whenever I am doing a water change. I do hear many different opinions about how much to change at once. I've been doing a 50-75% change weekly for months and I haven't lost any fish. Actually, the fish all seem to be a little bit more active after a change. The good news is that everyone is looking healthy and doing fine! I will definitely be much more careful with moving things in the tank during a pwc. Maybe this is a sully question, but do you guys usually vacuum under rocks and driftwood or just go around it?

 

[f1shg33kz]

It's good to vacuum under decor every once in a while. Waste can build up underneath them.

 

[Alyxx]

I get underneath the rocks and wood when I vacuum and once every couple months I pull all the decor out of the tank and vacuum where it all was. I have some serious poop machine plecos and the poop gets under everything. So from time to time the sand needs a really good cleaning.

 

[MurderComplication]

Some of the other members have had a similar problem, and I had an encounter like it as well. Where - as you mentioned before, soon after a water change a fish ends up dead. For some the fish seems to be acting erratically, or just simply lay on the bottom or top dead soon after.

 

[Crobb]

My tank is stocked to the max and I don't do that hefty of a water change. I have a great filter that helps with keeping my water clean. I wouldn't do 75% a week. I would do 35. As long as you have good circulating and plenty of oxygen in the water you should be fine. I have had my tank for almost 2 years with over 20+ fish with some Horny cray that keep multiplying and a turtle. I have only lost 2 fish since my tank had been fully established.

What size tank do you have? And what size fish?

 

[Mmil9533]

I have a 55 with 6 rainbows, 6 harlequin rasboras, 6 pristella tetras, 6 cardinals, a bristlenose, and 6 cories. The fish are all pretty small except for the rainbows and pleco. It is a little overstocked (found aquadvisor a little too late:/) but these are the first deaths I've had and I haven't added fish for months