Mold inside of Fritzyme 7 lid

[Beckybettas]

I found black mold growing inside the lid of a 1 gallon bottle of Fritzyme and just want to give every body a heads up. I figured this was not a good thing and tossed the bottle out. The bottle had only been open for a month so not really that long but how long does it last for other people? Should it be kept in the fridg ? Thanks

[Guppysnail]

I’ve not used this product but on the website it says it must be kept in a cool and dark place.