If they were fine in the store and then you get them into you tank and they go to the upper corner and have trouble uprighting and get stuck to the intake, it's the acclamation (Ph shock) I'll bet if you check the water at the shop vs yours you'll find a big differance. As an example a Ph of 6.5 to 7.5 is huge and would take all day in bucket with a drip to adjust correctly. Juvi Angles can be very delacate also. If all your water parameters are good it's Ph related.
