I like uncramped. When these guys get larger I am going to upgrade their tank again and just keep these three in it so they'll have lots of room. I like how active they are when they have swimming room.
i voted uncramped i like having room for them to move thatys why i sold 2 of my reds to make way for a piraya and will upgrade in june to a 90 gal tank and add 2 cariba ,5 in a 90 should be ok not cramped at all .the 20 gal per fish rule i dont go by a little over is ok but not way over
A lot of people on this site go by a general rule of thumb of 1 piranha for every 20 gallons. Personally I'm less conservative. I usually go with 10gallons per piranha. I feel a slightly cramped tank keeps all your p's in check and honestly looks much better. I mean go to your lfs or even to shark aquarium and see how many fish they put in some of these smaller tanks.