Clownfish Deliberately Attacking Tankmates Help

I've had a 32-gallon biocube with a single ocellaris clownfish for a year and a half. Two weeks ago I added a purple firefish and royal gramma to the tank and the clownfish had no issues with either. Suddenly a few days ago the clownfish started going out of its way to attack the new tank mates. It isn't just defending its territory it's deliberately going after the others. I believe the clownfish is in the process of becoming a female because it is looking much larger. Lately, I've been letting the clownfish sit in a net alone in isolation. I tried one day let him back then tried two days and just let it back in the tank. Each time I release the clownfish it is even more aggressive. I have just caught the clownfish for the third time and it is floating in the net. Should I leave it in for a week and is there any hope to reduce it's aggression?

 

Clown fish are damsels. They can get very aggressive in smaller tanks. Maybe try to move things around a bit or leave the clown out for a while then try again. He/she thinks that tank is theirs lol. Probably should have added the other fish first. But you can try and leave him out for a while in another tank and see if that helps at all.

I use to have a pair of clowns that always attacked my hand if I were moving coral around lol. They are very possessive of their homes

 

Yea I have had clownfish in larger tanks before that have been model citizens. I've never experienced anything like this before even when I had a clarkii. I think after a week of being in the net if it still acts up I'm going to have to take it back and wait till I add my final two fish a neon and yasha goby first before thinking about another clownfish. It's a wyoming white though gonna be very hard to give up so I'm really hoping to reduce aggression instead.

 

This is established clown behavior. They can be super aggressive to new tank mates in smaller tanks. Unfortunately the clown is probably going to have to go. You could try using a mirror for it to take it's aggression out on something else, but it sounds like it's pretty set in it's ways.

 

Very disappointing I may have to set up a small nano tank just for it. If I return it, I definitely will not buy any replacements until all other fish have been added.

 

I think one of the main causes (other than clowns being jerks in general) is that you added the clown first instead of last. Usually you want to add the most peaceful fish first, and add the most aggressive last.

 

Yea that was a mistake, lesson learned. I'm currently on day two of the week-long isolation. I moved it from a net to a breeder box. I was hesitant because the breeder box is clear as opposed to the net which kept it from seeing the rest of the tank. If anyone has any tips whether the net or breeder box makes a difference please lmk. I will keep you all posted on its aggression when I release it back to the tank. If the aggression continues I will purchase a small biocube to move it to.

 

I don't think just seeing the tank will make a difference, maybe make him watch you rearrange the scape and move the spot he claimed lol!

 

The breeder box is much better than a net as it's designed for the fish to be in there at least a few days. It will be less stressful on the clownfish as long as it is getting flow in the breeder box. Sometimes the time out works as does using a mirror for the clownfish to take it's aggression out on. My coral beauty is a near model citizen but look how it responded to seeing it's own reflection in a mirror (I was using it on an aggressive Yellow Tang at the time):

 

I wanted to keep it in the net so he wouldn't see the tank actually. I'd assume their memory isn't good enough to remember their territory after a long enough period away from it. But currently, it is floating in the clear breeder box. I just have so much live rock that I'm really not willing to rip the tank apart so if the aggression does not settle out he goes.

Great idea using the mirror. If I release him in the tank next week and still is attacking the other fish I will tape a mirror in front of the tank right near its cave.

 

So this morning I decided to add the clownfish back while feeding. He's still occasionally chasing the firefish but the Royal gramma put up a fight so the clown isn't bothering it anymore. The firefish doesn't seem too bothered but I'm worried over time the stress may lead to illness. Wondering if I should see how this plays out over time or just take the clown back now.

 

I would wait it out, but closely monitor just in case.

 

As long as I don't see any torn fins I'll probably just leave it and hope for the best. Definitely not adding anymore fish to this tank.

 

Beautiful hardscape, I bet the fish love it.

Sounds like a good plan

 

Thank you. I went to a zoo in Nashville where they stacked the rock up the sides of the glass which was my inspiration for this. Once I get all the green algae under control I will begin adding some soft coral.

Here is a full view