This is the second bottle we ordered that came with these white strings inside the bottle. We tried to contact Kordon but their email is not working. Anyone knows what is this?It took a long time for it to work and few dead fish.This saved my fish it has been living for an additional 6 months, none of the petstores had it and this was so useful. Be careful to never use too much you could poison your fish.The amount of copper in this product is basically zero. It's a scam. Do not buy!!!!The directions need to be more clear! doesn't say if you need to add copper Aid every day or the necessary amount one time for a whole month. I've had it going for about 2 weeks now in a 40 gallon tank and the fishes show no ImprovementThe price is great, until you realize how diluted this stuff is. The instructions say to add 5mL per 4 gallons. I am using a 20 High tank, so there should be a little less than 20 gallons of actual water. After adding 95-100 mL of this stuff my Hanna checker reads 0.45 ppm. So after adding about 4x times the amount they say to add, I'm still nowhere near the therapeutic range of 1.5-2 ppm. Don't waste your time and money! If you do really want to use this stuff, you would have to buy many bottles to actually make it effective.Doesn't work My fish died after using it following the instructions.