Unknown cause of guppy fry death??

HI all so I recently had a bunch of guppy fry! Yay... So I moved them to a new ten gallon tank. Using a new filter with old media and their old tank water. Just today I noticed their gills turned a bright pinkish colour and the whole group just dropped like flies. First I thought it was the water to I tested it, but the kit read 0 ammonia, 0 nitrites and 10 nitrates ph 7.2 which was the same as the original tank. I moved them a week after they were born. I really have no idea what the cause of their death is and I want to know what I can do in the future to prevent this! Any ideas are helpful thanks

 

Causes of reddened or pink gills -

Temperature, To high or low pH, Toxic nitrogen compounds, Chlorine, Lack of oxygen(hypoxia), Metals, Poison from PVC products, Cleaning products from spray, Soap or detergent residues, Smoke or Paint fumes, Bacterial bloom.

Any red flags popping up?
Hope this helps.

 

I noticed a filmy sort of layer on top of the water this morning. Could that be a residue of some chemical before?

 

Possibly,
Things to consider-
Did you wash your tank, did you rinse soap residue properly?
What is the old media in your filter, how long had it been not in use, did you leave it with fish poop sitting in water?
The tank you previously used the old filter media in did it possibly have sick fish in it and that contaminated the media?
Did someone spay air freshener or bug spray in your fish room?

NB. Hopefully someone can assist you concerning more of the testing of pH and ammonia and nitrates and stuff as I am not into the high tech setup style of keeping fish "if it is possibly one of those things that could be wrong"

 

I rinsed the tank with water before adding my water. Maybe I didn't rinse it well enough. Seems like the only logical explanation for the residue thanks so much and hopefully my next batches of fry don't have to suffer because of my stupid mistakes

 

Don't beat yourself up about it, happens to the best of us. At least you know that guppies are prolific breeders so I'm sure you'll have many new fry to look forward to.

 

One of the cool things about breeding guppies is that you are able to put a lot of experience under your belt in a short space of time because of how fast they reproduce. Don't be to hard on your self sometimes things like that are just unexpected at the level you may be at but now you know and you can check that as a notch on your belt of guppy knowledge
Happy guppying and I'm sure you'll have a new batch again soon.

*Guppy are omnivores, guppy fry will eat the moss that grows on aquarium plants and the glass, the moss grows when you have sufficient light on the tank "sunlight or fluorescent bulb but you don't want the light to intense.

 

Thanks so much for the help! Yea I guess it is true that there is a lot to learn! Gonna clean that tank real good and hope for the best for my next batch of fry!