COLOZU asked in PetsFish · 1 decade ago

Mysterious Aquarium Die Offs?

Over the past few months I have had numerous die offs of my guppies seemingly occurring in a cyclical pattern.

The tank was cycled starting in June and by late July all water parameters were ideal. I added 3 fish at that time (all guppies). They did very well for 5 weeks then died off in a 48 hour time. In the 48 hours I treated for Ick, and checked the water parameters ever 4 hours or so. The water maintained the same ideal conditions through out. Fast forward a few more weeks, and I let the tank run and cleaned everything. I gave enough time to recycle the tank if it needed it. The water parameters were all ideal. I added 3 more fish and they did find for about 5-6 weeks and ended in the same result. This time I treated for parasites, but within 48 hours all except 1 fish died. I slowly cleaned the tank and treated for parasites a little longer. Fast forward a few weeks I added two more guppies from reputable fish breeder and they have been super active and thriving, even contributed a few fry to my tank. 5 weeks later both of the fish I bought, shows signs of illness (red gills, rapid breathing, hiding in corners of the tank, decreased appetite) and one died within 48 hours. In speaking with the breeder they suggested I treat with an anti-biotic and it has seemingly done nothing to the one remaining fish who is getting worse and worse.

Water parameters have maintained through out as follows:

PH 7.6

Ammonia 0

Nitrite 0

Nitrate – 20 ppm

Alkalinity – ideal

Hardness Ideal

I have tried multiple measuring kits and have had my water tested, has always read as above.

Any Ideas?


Water is maintained at 78-79 degrees Fahrenheit. All the decorations are met for aquariums and for cleaning I am using hot water and an algae scrubbing pad.

2 Answers

  • Anonymous
    1 decade ago
    Favorite Answer

    How large is the tank? What kind/size of filter do you have?

    Guppies are particuarly sensitive to over stocking and can develop health issues from this such as mycrobacteriosis, and other otherwise dormant potential diseases.

    Do you have any sort of sprays, like plug-ins, or scented candles? Perhaps use cologne, febreeze, perfume, lysol or anything like that? These can settle in your tank, poisoning the water without setting off a regular test kit.

    Rapid gill movements, swelling and redness usually indicate high ammonia levels, though yours read zero. Something is clearly affecting them. I'd up their temp to about 80-82, and add a bubbler to help oxygenate the water; higher temps equel lower dissolved oxygen levels, and with their already compromised systems, it's best to cover all the bases. I'd also consider adding some freshwater aquarium salt, just to help along with the heat, inducing a sort of fever and help to prevent any secondary infections and fight off their potential current one.

    If these guys don't make it, I suggest a complete tear down and sterilization of the tank. You could have air born chemicals, or some sort of disease infecting the tank. I'd also recommend taking a very close look at you ornaments and plants, is everything meant for aquariums specifically? Even terrarium ornaments have warnings not to be placed in an aquarium. If anything is fading or chipping, or is questionable, I'd suggest foregoing it just in case.

    Best of Luck!

  • 1 decade ago

    What have u been using to clean your tank and decorations? And what temp is your water? Do you have any decorations in there that aren't meant for a fish tank? The red around the gills suggests ammonia poisioning but your water shows no signs of ammonia... very strange.

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