I won't buy a third one, because of the tank size.
They don't fight and they don't chase eachother, so i don't see a problem. In fact they seem to be more calm and the color on them is better than it ever was.

Sometimes If their years old an odd number of 2 wont matter as they have likely been subjected to numerous owners, tanks and stock to be non specific! Adults 2-3+ years old have seen and been thru what I can't only interpret as a 'foster homed/negleted life' of ups and Downs (mostly Downs!) Passed off fk to fk, eventually finding a stable home with hopefully good water and decent space to swim about and be the animal its partially domesticated/wild to be!
But a lot of 1st time fk for some reason buy red belly piranha as babies/teens/adults often not knowing most if not all of their specific needs! A lot of 1st time piranha owners will sell them off when they hit the 6" or less mark for reasons I can only guess as to them NOT portraying their Hollywood counterparts when it comes to aggression, eating habits and pure murderous appetites these FISH have been known to have!
But any honest fk can have a valid reason for rehoming/selling their piranhas, such as BUT NOT LIMITED TO; moving, down grading, loss of work, wife, wife not getting bit in the neck and dying a gruesome death thus avoiding a financial ruin of divorce etc....etc
For the true/honest FK, such as most of us, we see practically in keeping these and many other fish as pets/friends in a space they can actually have a swim in and enjoy the domestication for years to come! After all piranhas in general spend a lot of time in the WILD watching their back and trying not to die from larger/smarter predators, dry season etc!
We can offer them a slice of their mostly natural habitat given a lot of time, water changes, maintenance, research etc! And those that have successfully kept fish for years know the gratitude that comes with such perseverance!
For fish that have lived the 'foster/re homed life' there is still hope of a good FK coming along and scooping them up to treat them like pets and give them a chance to enjoy life and be a fish! Instead of posting adds on CL with pics that are way older
Props goes out to anyone and everyone who has helped/rescued fish that need a healthy/consistent dig to call their own!!!!
Cheers op! I once did the same with multiple piranha/fish and if you undoubtedly see tranquility in the aquarium then thumbs up and keep it going! Don't let the flame of FK passion burn out due to boredom! Like any animal they will get old, max out in size etc, become less active etc
×Go S. Vettel #1 Infiniti Redbull! 4x WDC!!! Congrats on another flawless title×
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Cheap way to decrease nitrates and keep your fish healthy: http://monsterfishkeepers.com/forums/showthread.php?t=504763