They can get quite large (14") but it takes a while(maybe 3 years).
I believe most keepers can't wait, and as they get older they become quite intolerant of any tankmates, except in the largest tanks. In a 300 gal, things may be less troublesome.
They prefer very high quality water, with lots of current.
I started with about 10 2" juvies from Don Conkel, the parents were easily larger than 14", he had in a large vat, probably over 300 gallons.
At 6" the alpha male started killing all other argentea in a 150 gal, then started on any other tankmates, (including regani, and a large managuense) it ended up alone, and hit over 12" before a power outage took it out.
I had another pair later, that spawned but after the spawn the male immediately killed the female and ate the eggs.
male
