Aquamid Vs Bio Alcamid for Buttocks Filler

Bio-alcamid and other fillers are probably a good option for the face, where the filler can be used on small areas. We are talking about using 2-5cc here. For the average buttock augmentation, though, the volumes are in the hundreds of cc's.
You cannot inject that amount of filler and expect a finely contoured result that is free of lumps or bumps. I also see questions on these very boards asking what can be done to remove permanent fillers. What happens as your tissue naturally moves wth the aging process ?
In the face at least, I don't think these permanent fillers move with the tissues in a natural manner.
Your own fat is a much better option, and implants a distant second.

Fat transfer remains the best filler for buttock enhancement. If you do not have enough fat consider implants.
Permanent fillers like silicone and hydrogel are illegal and a BAD idea.