iv kept discus a few times but due to a move i sold all my old stock iv just started to buy some new stock am not to bothered if they breed but if they did then thats a plus. i bought 2 lovely adult discus to start with and they got on well together iv just added a new discus to the tank but doing this has made the larger one of all 3 quite aggresive towards both his tank mates (even tho he wasnt before) could this just be a sign of domanance or could there be a pair in the small group. i could really do with help on this one i never had this problem with any iv kept or breed myself in the past and dont want one or both of the other two getting stressed.and also the larger one will let the smaller two feed but once they have fed and all food gone and they are swimming around again it chases them again which means they both are hiding at each end of the tank while the bigger one is free to do as it pleases 
