Clownfish suddenly acting very aggressive

[marciemp]

I have a female oc clown who is suddenly acting very aggressive to a 4 stripe Damsel. We have had the clownfish for over a year (Dec '06) and we got the pair second hand with our tank, I believe the previous owner had them for a few months. The tank was 72 gallons and came with rocks, equiptment, the clown pair (who were small and the same size as each other), a blue tang, yellow tang, yellow tail damsel, and a yellow watchmen. A few months later we upgraded to a 92 gallon corner bowfront. All was well, this was about a year ago.

The clownfish grew like crazy since we got them and one is now much larger than the other. They spend a lot of time in the back corner of the tank cleaning and organizing the sand back there, they have dug a little pit. Probably about 11 months ago we bought a 4 stripe Damsel, it was small, and I had read in several books from the library that it was not too agressive. It quickly bullied the yellowtail Damsel into hiding in the rocks, where it still spends most of it's days. The tank was peaceful for many many months.

Just in the past 4-6 weeks the larger clownfish has begun chasing the 4 stripe Damsel. At first it was just a bit here and there, but I noticed in the past few days that she was relentless. They go around and around the rocks. Every once in a while the Damsel slips into the rocks and the chase stops, but as soon as it comes out the clownfish starts again. The damsel will go and hide between the powerheads and the chase will stop again but every time it comes out the chase starts again. They are so fast it is hard to tell but I think the clownfish is even nipping the Damsel, but with no visible damage. I don't watch the tank all day long, but for the time I watched it today they did this the whole time and it seemed very stressful. By the end of the day it almost seems as though the pair are tired, as the clown will lay off a bit, like she's taking a break, but if she sees the damsel or he gets too close, the chase starts again. The damsel never starts the fight, he is always just hanging out when she starts.

There have been no additions to the tank. Not sure what has triggered this aggressiveness. The clownfish is getting very large, and the 4 stripe Damsel has grown a lot too. All of the other fish get along very well and seem healthy, except the poor little yellowtail damsel who hides all day and has a big pop-eye (came that way with the second hand tank, has never recovered, was probably used to cycle)

Marcie

[dsaundry]

Your clowns are probably setting up to breed. They are establishing territory and any fish they deem a threat will be chased off. I have a maroon clown in a 90g and it is in with a trigger, purple tang, and even though it is the smallest fish in the tank, there is no doubt who the boss is. Its his tank and he protects his anemones fearlessly..You may find it settles down if there are lots of hiding spots in the tank, if not you may find a dead fish one day.

[marciemp]

The thing that is weird is that the clownfish look like they have been getting ready to breed since they have been in the new tank (about a year now). They established themselves in one front corner for about a week or two, then they moved to the back corner. They have been wiggling in the sand, brushing it out of the way, and wiggling against the glass ever since then. They look like obsessive compulsive fish, cleaning that corner. Like I said though, they have been doing that for about a year, but they have never laid eggs that I know of. We have only 4 groups of soft corals (zoa's), and so the clowns seem to be hosting the corner. And the agressivness only started a month ago or so. Before that everyone seemed to get along.

I feel bad for the damsel as he does seem pretty stressed. I guess if it continues we should maybe find him a new home, although he is my 4 year old daughter's fish, and we only have the one tank.

We are considering rearranging the rockwork anyway, as we are thinking of adding more rocks, maybe that would help.
Thanks,
Marcie

[PoonTang]

If your clowns are acting that agressive then they probally have already laid thier eggs. My pair laid thier first batch about 5 days ago and what a change in thier behavior. have a look very closely, the eggs are hard too see.

[BC564]

I can tell when mine have laid eggs or close to it.....they attack my hand when Im cleaning or arranging a coral....the larger one(female) has drew blood from me on occasion....she is nasty.....

[Geofrog]

Once the clownfish start to breed, they lay eggs every two to three weeks. Or at least mine do. Mine lay their eggs on the rock work right beside their host anemone. They did keep to the small area where they currently lay their eggs for some time before I noticed that they started breeding.