Help I think water changes are killing my fish

vino32

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I recently had added six zebra danios to my 20 gallon tank, then shortly after doing a ~20% water change 3 of them had died. So I went to my LFS to buy a few more, then after doing another water change another one has died. I have two honey gouramis which have been completely fine with the large WCs. Are these water changes killing my danios? How much and how often should my WCs be then?
 

ghostdawg

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Are you adding tap water and then conditioner? You should do that before you put water into the tank. Make sure temps are the same as well. Is the tank cycled?

Are you testing the tank water? I usually do a WC once a week on Sat or Sun.
 
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vino32

vino32

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ghostdawg said:
Are you adding tap water and then conditioner? You should do that before you put water into the tank. Make sure temps are the same as well. Is the tank cycled?

Are you testing the tank water? I usually do a WC once a week on Sat or Sun.
Yes I always use conditioned tap water. The temperature is consistent at about 74 degrees F. The tank has been up and running for 3 months and tests show that the tank is cycled. How much water do you change each week?
 

ghostdawg

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vino32 said:
Yes I always use conditioned tap water. The temperature is consistent at about 74 degrees F. The tank has been up and running for 3 months and tests show that the tank is cycled. How much water do you change each week?
I usually change between 25% - 50%, weekly. It is odd that danios are dying like this. I've had 6 total for a year, first in my 10gal and now in my 20g long and only lost 2, but not from WCs.
 

FishBoy101

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I did some research (by that I mean surfing google), and I found that 74 is quite too high. And honey gouramis need 78-82, these two fish cannot live with each other.
 

MrsPancakes

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I have an overstocked, planted tank with 28 zebra danios. I do 50% every three days. It’s never the water change, but rather the logistics of the water change. Conditioned water (I recommend Prime because it also takes care of heavy metals), water temp difference, ph fluctuations, and so forth. Also, make sure you are acclimating new fish by floating them for an hour and adding a cup of your tank water to the bag every 15 min. Hope that helps.
 

Basil

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MrsPancakes said:
I have an overstocked, planted tank with 28 zebra danios. I do 50% every three days. It’s never the water change, but rather the logistics of the water change. Conditioned water (I recommend Prime because it also takes care of heavy metals), water temp difference, ph fluctuations, and so forth. Also, make sure you are acclimating new fish by floating them for an hour and adding a cup of your tank water to the bag every 15 min. Hope that helps.
This. Do you know the ph and TDS of your tap water versus your tank? Big swings in water parameters were killing my fish after water changes. Or at the least, stressing them out greatly.
Until I tested my tap water (which is well water), I didn’t realize how different the ph was.
 

AvalancheDave

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Twenty percent makes it less likely for water changes to kill fish though.
 

RedGallant

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FinalFins said:
Beneficial bacteria can take quite a lot before being "cleaned" off. I doubt they were vacuumed out since BB sticks to hard surfaces in the tank and not free-floating in water.
Do you know if the OP was gravel vacuuming with the water change?
 

Utar

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Your danios dying as nothing to do with water changes, no way and no sir. It has to do with water temperature. Honey Gourami and Gourami in general need much warmer water then danios, high 70's to low mid 80's. Danios need temps in the low 60's to low 70's, and yes they will live for a year or so in higher temp water if you buy them young. They however will not live much longer then that. That day comes and they start dying, because the higher temps speed up their metabolisms basically burning them out.

You can live in a really warm room, but you want be comfortable and in time will start developing issues caused by the warm temp of the room. Lack of sleep, eating, etc will start to take its affect your health.
 

FinalFins

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Utar said:
Honey Gourami and Gourami in general need much warmer water then danios, high 70's to low mid 80's. Danios need temps in the low 60's to low 70's, and yes they will live for a year or so in higher temp water if you buy them young. They however will not live much longer then that. That day comes and they start dying, because the higher temps speed up their metabolisms basically burning them out.
I keep my honey gouramis in 72-74 F water. They have been doing well since I got them. And I belive that honey gouramis are fine in 74 and really only need 80+ for breeding purposes . I don't mean any disrespect but in general is a very loose term. There are some gouramis that would prefer 80 ~ F (chocolates) and there are colder water gouramis (eyespots), which like 71~ F (and can go lower) as a stable temperature .

I really doubt it was the temperature. No way a 74 degree tank kills fish within 20 minutes. It speeds up their metabolism but it doesn't shorten life to a few days from store to tank.
 

Utar

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FinalFins said:
I keep my honey gouramis in 72-74 F water. They have been doing well since I got them. And I belive that honey gouramis are fine in 74 and really only need 80+ for breeding purposes . I don't mean any disrespect but in general is a very loose term. There are some gouramis that would prefer 80 ~ F (chocolates) and there are colder water gouramis (eyespots), which like 71~ F as a stable temperature .

I really doubt it was the temperature. No way a 74 degree tank kills fish within 20 minutes. It speeds up their metabolism but it doesn't shorten life to a few days from store to tank.
With all due respects, I did not say a few days, I said a year or better. And yes you can keep Honey Gourami at 74 which is their low end and they will be ok. But not danioes for over a year are better because that is on their high end. I know this from my own experience in keeping both fish. I had danios and dwarf gourami in the tank with temps of 74 to 75. In a year's time the danios started dying off one by one. But I expected this in learning about it after the fact of getting the danios.

When you temp match the stock going into an aquarium then the entire stock does better and last longer. But when you don't match then try and meet the temp somewhere in the middle, then in time things start to go bad.
 

FinalFins

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Utar said:
With all due respects, I did not say a few days, I said a year or better. And yes you can keep Honey Gourami at 74 which is their low end and they will be ok. But not danioes for over a year are better because that is on their high end. I know this from my own experience in keeping both fish. I had danios and dwarf gourami in the tank with temps of 74 to 75. In a year's time the danios started dying off one by one. But I expected this in learning about it after the fact of getting the danios.

When you temp match the stock going into an aquarium then the entire stock does better and last longer. But when you don't match then try and meet the temp somewhere in the middle, then in time things start to go bad.
I did realize you did not say a few days but the OP says that they only recently added the fish to the tank.
 

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