Pajama Cardinalfish Problem?


New member
Does anyone have any experience with having two Pajama (Spotted?) Cardinalfish at the same time? Everything I've read says they go really well together. A little over 2 weeks ago I got 2 small ones from the LFS and put them in my 10g quarantine. I tried feeding them flakes or pellets for 2-3 days but they would not eat. Went back to the store and got frozen mysis and brine shrimp. They were eating fine but the larger of the two seemed to be bullying the smaller one. For the past week or so I have noticed the smaller one eating less and less, until yesterday when he did not eat at all. He looks like he's having a hard time swimming and looks pretty "tired".

My first time QTing anything (first fish, actually). Ammonia levels have stayed 0 pretty consistently, with it going up to 0.05 one day last week. Been doing water changes, dosed a very small amount of Prime that day it went up to 0.05. Been regularly cleaning the HOB which just has sponge filters in it. Also have a bubble wand in there, so I doubt it is an oxygen problem.

Is it possible that the bigger fish just bullied the little guy to death? I never saw him actually make contact, but he would dart all the way from across the tank to attack him.


New member
They are fine in even in groups, actually. An occasional chasing is not unusual but this is usually benign. I always think they have very short attention span...the chaser stoPs abruptly and seems to have forgotten what he was just doing :D I do think that they should be in a big enough tank to have room to lose the chaser. I have 2 big ones that were tinier than a nickel when I got them. One was added later and it was smaller than the first one. They were fine from day 1. I did not QT. Note that each fish is different.