Glitch in level?

I have been stuck on level 4516 for at least a week and it appears there is a glitch where the fish only randomly take out the black tile blocks along with any other tile which makes it virtually impossible to get to the 3rd screen (and there is a 4th) with more than 5-6 moves left. I have only made it to the 4th screen a few times. Have never had this much difficulty with a level before