Thinking about RBP's, just a couple questions...

[Nubster]

I've always admired them, now I am thinking about getting some. I have a 75g tank. Right now it's full of shrimp. I'll be moving the shrimp out and into another tank. Filtration will be handled by a couple canisters and a large HOB (AC 110) so that should be covered. My question is, what's the max number I can have in the tank as adults without crowding? I'm thinking 3-5. Also, is it better to keep them in odd numbers or does it matter? Last one, once I am able to setup a larger tank in a few years, how difficult is it to introduce more fish to the pack? Thanks.

[Chub_by]

In a 75 I'd say maximum 4 rbp's.. it doesn't matter if it's an odd number or not, but you shouldn't do three or one will probably be picked off.

[Nubster]

Thanks. I know a lot of smaller shoaling fish it's recommended to keep them in odd numbers even though you'll inevitably have deaths which could make the numbers even. Just wasn't sure if RBP's fell under that "rule".

[Chub_by]

Rbp's will most likely pick off the weakest fish when kept in odd numbers, so 4 really would be best for your tank

[Deubie Doo]

I agree, 4 will be good if you want them to get full grown. one will most likely get killed, theres no way to stop it just happeneds. its easyer to get them to get along if you get them small to start off with, they grow fast so dont be bumed starting small. note: -> what I found that helps with them being skidish is to only put one thing in the middle of the tank that they can hide behind. then as they grow take it out so there in the open and then they cant hide. once they get in the habbit of not running from you every time you walk by or go up to the tank then you can dress up the tank. sounds bad but it helps.

[F1 VET]

Depends on the size. You could raise a shoal of 10-12 from nickel size to pre adult 2-4" and then upgrade. As far as full grown id say 3 10-12" rbp max in a 75! Piranhas are skiddish, lower temp, high current and proper diet/water help!!!

I use amazon bio colorant and that helps keep them calm, i have 5 5-6" rbp in my 90gal w/ fx5 ac110 1100gph fan and 9watt uvc, i keep the nitrates below 30ppm and they grow fast. Awesome fish, i love them!!

#1 S. Vettel

[Nubster]

Thanks again for the additional info. So what would be considered lower temps? Right now the tank is kept in the mid 70's for the shrimp. I wish I could do a larger shoal of small fish but I know for a fact that I won't be able to upgrade before the fish needed re-homed. I am looking at 2-3 years before I am able to move from this house to a new house where I can setup a 100+ gallon tank. My ultimate plan is to do a plywood build of around 250 gallons unless I find a killer deal on a huge glass tank in the future.

[jp80911]

if you are doing rbps, with good filtration I see no problem with 4-5fish, they won't get to 10-12" over night so you can always upgrade or downsize as needed. they have the potential of reaching 12" but most likely around 8-10" and that would take sometime (few years depends on what size you get them at). growth typically slows down after they hit 6" and at that size you can reduce feeding amount/frequency so they can grow to proper head/body ratio which means it may take even longer for them outgrow the 75g.
you can keep temp at around 75F, with lower temperature their metabolism slow down a bit so watch your feeding amount/frequency.

[ballinouttacntrol]

+1 we're talking multi years before you'll reach 8 inches. Slightly overstock


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[Nubster]

Cool. I thought they'd grow out faster than that but that's good news that they can take years...by the time I'm ready for them it will be late summer, so that will give me some good time before I have to upgrade the tank.