2 fish dead with no visible cause

[Neleono]

Hey, my sister just set up a fish tank a few weeks ago, we set it all up, let it run, and bought 4 fish Monday (The 7th). We got 2 neon tetras and 2 guppies. One guppy died about 4 days ago and i didnt think much of it. Though it was sad, i thought it was (A term used by the reptile community) pps or post purchase syndrome where the stress leading up to going to their new home ends up killing the fish. I tested the water every day and it has been safe since the fish have gone in, and we took a sample to PetSmart and they tested it and said it was perfect. Tonight, my sister comes in to my room and tells me another fish has died. I go in there, take him out, test water and everything is fine. No apparent reason for this second guppy passing. The temperature is maintained at a constant 79-80 degrees with the heater, the filter is always running, theres an airstone on in the day time, and feeding happens daily. Is there anything i could be missing here or more tests i could be doing? How can i fix this or can i not? Is this a coincidence of misfortune? Any thing helps and i hope another set of brains could solve this. Thanks, Nele. (Tank stats below, please ask for any more info you might need) Side note, i read that they are susceptible to large environmental changes but the statistics below haven't changed since purchase.

Ammonia : 0
Nitrate : 10
Nitrite : 0
Hardness : 170
Chlorine : 0
Alkalinity : 140
pH : 7.1
Temp : 75
Tank environment : 10 gallon with 4 fake plants, a small live plant, 4 fish (Pre Death)

 

[AdoraBelle Dearheart]

How did you cycle the tank within a week? Did you seed the filter with bacteria from your tanks?

You've always had zero nitrites and ammonia since setting it up? When did nitrates first appear?

 

[Neleono]

Hi, now that i look back at time, i guess it was more than a week, more like 2, and i used a product called bio-start to strengthen the bacteria (idk if it rly works). I started testing the tank after 2 days of cycling and i haven't ever had ammonia or nitrites.

 

[FishBearer9845]

2 days is not long enough unfortunately, if it is a fresh tank, even with these bacteria in a bottle things it can take up to 6 weeks (experience)
You should invest in the API master kit, it tests ammonia and nitrites amongst others. Is your tank heavily planted? I find it odd that there have been no ammonia or nitrite readings of at least 0.25 - of which even minimal can cause lasting damage. Do you test your parameters every day?

 

[Neleono]

I did cycle for about 4 days which in hind sight was a stupid idea, I do test every day because this tank is new and im afraid of something going very wrong, i also do have an api kit, i will try it and see if there are any differences (the strips im using might be off).

 

[Neleono]

I just did the kit, and there were no differences between what it gave me and what i already listed.

 

[FishGuest5123]

Your water is too warm for both guppies and tetras. Drop it to about 75F.

 

[itiwhetu]

I agree with Deanasue the water is to warm. Also make sure that you have your tank well planted. Between 30% and 50% of your tank should be planted. This will help to keep the tank stable.

 

[Regalz]

So from what i can see, it was maybe the tank set up time and maybe if the pet store had them in cold water and you changed them to warm or visa versa, it also may have been a bit of stress. I've lost fish to stress before. Don't fret it though, you know for next time. Unfortunatly as a new fish keeper you make mistakes and lose some fish. I have had fish for more then 7 years now. I still occasionally stuff up although my stuff ups don't cause dead fish anymore.