Hi,I am sorry to hear about your Wrasse, but I would submit to you that It wasnt the Flat worm Exit that got him.After using the product I am sure that you did see Flat worms Fleeing,But there were many more Dying and releasing toxins in your water which probably killed your Wrasse.I just switched all of my Rock and fish from my 65 to a 120 and I had a bad problem with Flat worms also in the 65.I know in some peoples tanks what I am about to tell you simply wont work, because you have too many things to move.But what I did as I was moving the rock from my old tank to the new tank, I set up a "cleaning station" in my garage.I took 4 Styrofoam coolers and set them up on a portable table.I then filled them up about 1/2 way with Ro water and put the proper amount of salt in each one.I then added a powerhead to each cooler to keep everything circulating.As I brought the rock out from my old tank, I would put it in the first cooler and give the rock a rub down with my fingers to get as many off as possible.I would then move the rock to the 2nd cooler where I used the powerhead to blow into the nooks and crannys and get more out.The 3rd cooler was the Flat worm exit dosed tank.I moved the rock there and let it sit for 30 minutes.The final cooler was use to rinse the rock off and blow out any Dead remaining flat worms with the Power head again.I then moved the rock into my new tank,and have not seen a one, nor did I lose any zoes or corals in the Process.Even my BTA went throught the process and he is fine.All the fish remained in the 65 until all rock was in the new tank,and then they were moved.They are all doing fine as well. Flat worm exit works very good and is Not harmful to your fish or corals.What is harmful to your fish is the toxins that the flat worms release when they die.For every flat worm I could see,I probably had 2 or 3 that I couldnt see! This is the reason that if it all possible,Try to separate your fish from the rock being treated. I think Flat worm Exit is an Excellent product as long as you take the Necessary steps outlined in the directions while using it. Hope this helps!