Question about my tank..

yes, but remember these are piranha and nothing is guaranteed just do a small water change and either take out you decor or move it around if there is none feed your now fish do wc and put fish in.....

to successfully add a new piranha to the shoal you may want to move some decoration around (to break up established territories) do a water change, and feed the fish about an hour before adding the new p (feeding them an hour before will make sure they are full yet still not in "feeding mode")


good luck with your p's


what size is the tank btw ?

if you still have the old tank you can get smaller ones and grow them out.
just curious, what size tank do you have now?

I read they own two 55s and an 85, looking at the avatar pic, could be the 85?

what's the footprint of the 85g tank? is it 60"x18"?
if so then I think keeping 5 in there should be fine as they don't get too big, probably 9-10" max and that will take a few years, if you do like them a lot and by then maybe you can upgrade to a bigger tank if you think they need more space. just make sure you have sufficient filtration to keep up with 5 rbps as they are messy eaters. what kind of filter are you using now?
do you still have the old 55g? if so use that as grow out for the new rbps and add them to the shoal once they are big enough.
you can follow what other have said about adding new piranhas to an established shoal. an other approach I've used many times with success is first scare the crap out of your current shoal with a net or something other than your hand (so that they won't bite you by accident) then add the new fish and scary the crap out of them all together. once they settle down together they'll be like best buddies.

looks nice, how big are those reds now? I'm guessing 4-5" maybe??
if you can provide the dimension it would be easier to see if you'll be able to house more rbps. you can have over 100 gallon of water but if the footprint isn't right you won't be able to keep too many. but from the looks of it it should have enough space but not 100% sure.
what are you feeding them right now? hope not feeders as they are not very healthy for your piranhas.
and if you can provide some information on the filter you are using we can see if it'll be able to handle couple more piranhas or you'll need to upgrade the filter or add more filters.