Behavior issues

I have to say that the P. venusta larvae died due to their behavior. Not bad behavior, but different behavior which I was not prepared for. These larvae like to sit on the bottom and I have not seen that in other larvae that I've worked with. Normally I clean the bottom of the larval tank on a regular basis but could not do so while they were sitting there. They were strong and fed well and I had plenty of food to offer but could not clean up after them well enough to keep water quality up. So I have made some changes to the larval rearing tank for the next run. Basically darkening the bottom and brightening the surface to see if that will help keep them off the bottom. I did have the opportunity with two small spawns to test if the larvae are attracted to light and they do seem to be which is why I am going with a darkened tank bottom on the next run.