can peaceful fish become aggressive

[LISound]

I just picked up 2 new fish. I've never been a huge fan of fish but now that I'm keeping SPS I needed a few more.
some history...

I have a 20 gallon that has had a single firefish, CB shrimp, and peppermint shrimp in it for the past 5 years.
the other day I added a flasher wrasse and a royal gramma.

Up to about a year ago, I only fed every other day. Since that I time, I started to feed the fire fish at least once a day...sometimes twice, but only what he could eat.

He really fattened up, I had no idea how much i had been starving him.
Well, in the process, he started to come out more and swim in the open waiting for food.

Well, the wrasse died today from something like ich, but much worse. His skin was pealing off, looked like fin rot.
Anyway, the gramma now is rubbing against rocks, looks like ich.

I believe Ich is stress induced.

After just feeding the 2 fish...my fire fish won't even let the gramma out of the rocks to feed. he goes right up to him and flashes.
I tried to feed the fire fish on the other side of the tank but as soon as he saw the baster go down where the gramma was hiding, he came right over and made sure the gramma couldn't eat.

Back to the subject of the thread...
do you think the fire fish has become so terratorial that it won't tolerate a real peaceful fish, or any fish in general.

I think now, that the fire fish stressed the wrasse out so much, it couldn't deal.

now the gramma could be next. I plan a tank upgrade for this system but not for another month at least.
I think even if i take all the rock and rescape, I'd just stress the both of the them out or would that work.
I don't even know if that will help the gramma since it would still be in the same small tank.

[mjw357]

Did you quarantine the new fish? perhaps they brought something with them?

[LisaD]

that also may have been too many fish for your 20.

fish in a small tank may become very territorial if they feel crowded.

[LISound]

I did not qt them. I was lazy and didn't want to set up the tank.
All other fish in the order are fine...I think there were about a dozen of them total.

the fire fish is now very territorial...but I figured since they are a peaceful fish, they would all get along. they are all listed as peaceful.
I think I would have had to put them all in at once?

[billsreef]

<a href=showthread.php?s=&postid=14465257#post14465257 target=_blank>Originally posted</a> by LISound
I believe Ich is stress induced.

Nope. It needs to be introduced, and if introduced it is not required for a fish to be stressed to get it. It's always worth spending the time and effort to QT.

As for aggression, firefish don't play well with each other, or any other fish of similar body shape. Same for the Gramma, except it's more common for the Gramma to be the more aggressive. In your case the firefish is already established, so that's likely why it's got the upper hand. The firefish likely wasn't hassling wrasse, just the wrasse was carrying a sufficient parasite/disease load to succumb.

[LISound]

ok. thanks.

the fire fish has a white spot or two now as well.
I never learn.

Time to break out the hospital tank. How long will they last with ich.
Can they make it to the weekend, not sure if i can tear down the tank this week.