the general rule for red bellies is 15-20 gallons of water per piranha. so i'm guessing that with adequete (sp.) filtration, you could keep about 8-9. good luck with the piranhas.
ya they gave u pretty good awnsers for keeping them for life but when i had them in a 125 i had 17 but they were all around 3 inches and as they got bigger i took a few in at a time to the lfs and kept 10 5 inchers in there for awile.
the general rule for red bellies is 15-20 gallons of water per piranha. so i'm guessing that with adequete (sp.) filtration, you could keep about 8-9. good luck with the piranhas.
da 20 gal thing is true but you an always over populate a lil bit without too much problems so I think u should be ok with 7. just be aware that a day or another, u could wake up with a situation like this...oh ****, picture dosent work. haha well....try to picture in ur head a dead p's head...less impressive I know...lol
You may also want to consider if your fish are schooling back and forth. I saw about 25 2-3" with some exodons going back and forth in formation in a 75. It was awesome.