How many PJ Cardinals Should I Have?

[Chortanator]

I currently have 3 PJs in a 55gallon, I'd like to get some more to fill out the space since the only other fish that are own in the open are 2 clowns and a royal gramma. I thought I remembered reading somewhere that they need to be in a group of odd numbers otherwise they'll bully one to death, is that true or am I misremembering/thinking of another fish? How many should I stock in a 55gallon? Bioload isn't an issue, currently at 1ppm nitrate.

 

[doubleshot00]

i bet you will be down to one one day.

 

[ISpeakForTheSeas]

Some recommendations I've seen include keeping odd numbers (3, 5, 7, etc.) and keeping large numbers (like 9-11+ fish) for schooling/shoaling.

If I remember correctly, pajama cardinals are one of the better species for it, so you (in theory) shouldn’t have too much difficulty. I don’t know why the odd numbers is suggested, but there might be some valid reasoning behind it. For the large numbers, the idea is diluting the aggression/spreading it out rather than focusing it on one fish. Not many people that I’ve seen are willing to dedicate the tank space to test this, but there’s speculation that it would allow for schooling with some of the more aggressive species (like wrasses).

 

[Chortanator]

Some recommendations I've seen include keeping odd numbers (3, 5, 7, etc.) and keeping large numbers (like 9-11+ fish) for schooling/shoaling.

If I remember correctly, pajama cardinals are one of the better species for it, so you (in theory) shouldn’t have too much difficulty. I don’t know why the odd numbers is suggested, but there might be some valid reasoning behind it. For the large numbers, the idea is diluting the aggression/spreading it out rather than focusing it on one fish. Not many people that I’ve seen are willing to dedicate the tank space to test this, but there’s speculation that it would allow for schooling with some of the more aggressive species (like wrasses).

Thanks for the info. I had originally purchased the 3 that I have to make my green wrasse feel more comfortable coming out of hiding, but these guys spend a lot of time in the shade of the rocks too, so I was thinking that maybe getting 2-4 more would make them a little more confident, too

They're not necessarily skittish, and it could also be due to how much live rock I have, but I'd love to see just a little bit more life in my tank other than my clowns and royal gramma

 

[vetteguy53081]

three and five are common shoals for the pajama whereas 3 typical for banggai.

 

[ISpeakForTheSeas]

One thing to keep in mind that might explain why they're hiding: cardinals are nocturnal. I don't know if this is the issue here, just letting you know in case it might be.

Some other fish you could consider if you're looking for more life/movement: gobies, blennies, and dartfish. From what I've heard, you really can't go wrong with a goby/pistol pair or barnacle blennies, and the zebra barred dartfish apparently does well in schools and is pretty active. These guys would probably be more active in the day.