well, rbp won't get that big so you can scratch that off your list. and you want a shoal then it leaves you caribes and pirayas but price of caribes could be more than your $25 per fish or even $50 per fish depends on your location and size of the fish. and piraya will be way out of your price range unless your lfs mistake them for rbps.
either way, once the fish do get to that big, the 125g won't be wide enough for them to turn comfortably but that's not gonna happen anytime soon (probably 6-7 years).
to give you an idea take a look at the link below, the tank is 200cmx70cmx70cm, that's 980L or 251.93 US gallon. the biggest caribe is 14", smallest is 8" they make the big tank look small.
http://www.piranha-fury.com/pfury/index.php?showtopic=189229
either way, once the fish do get to that big, the 125g won't be wide enough for them to turn comfortably but that's not gonna happen anytime soon (probably 6-7 years).
to give you an idea take a look at the link below, the tank is 200cmx70cmx70cm, that's 980L or 251.93 US gallon. the biggest caribe is 14", smallest is 8" they make the big tank look small.
http://www.piranha-fury.com/pfury/index.php?showtopic=189229
