troublesome cardinal... advice?

[lsvagabond]

I have a 20 gal long that i took over about 3 weeks ago. It came w/live rock, mushrooms a bubble coral and one pajama cardinal. After it all settled down a little i could not resist the urge to pick up a cleaner shrimp. The guy i took it over from was feeding pellet food so i also picked up some sally's brine shrimp. After about a week of this i have been able to sit down and notice that my cardinal is getting a little mean. Today i saw him repeatedly taking shots at my cleaner shrimp... Do i need to get rid of him or is he just getting used to sharing the tank? I value the shrimp much more and also plan to add non aggressive fish. I kind of like him but not at the expense of a brighter future. Any advice?
mike

 

[botp2k1]

I have not seen pajamas mean, chromis yes, not pajamas, they just stay pretty much motionless. Can you be more specific in how he takes "shots" at the shrimp? Cleaner trying to clean and the fish takes a dislike to it? Or cardinal actually going out of its way to go after the shrimp? You could move the LR around at the same time you introduce new fishes.

 

[lsvagabond]

The way I saw it happen was like this. After feeding my room mates and stuck around to keep watching the tank and we noticed the cardinal hovering nearby to the shrimp and then dart over to nip at at him. they would both back off a bit then he would do it again. Sometimes going after the shrimps antena sometimes at his back. He took a nip at a hermit cvrab walking by as well. Very strange. Do you think changing him over to brine shrimp from pellet has something to do with it?

 

[botp2k1]

My first thought is to imagine a cardinal or any other fish that has laid eggs and is aggressive in protecting them. I don't think it is in this case, see if it continues, if you really want, give the cardinal away to a local hobbyist. I highly doubt changing food has anything to do with the behavior. Hopefully you are feeding enough. I have seen others not feed enough due to a small bioload (1 fish in a large tank, etc.).