Clownfish Aggression?

Epicanimal · May 25, 2019

I have a pair of domino clowns in my 20 gallon tank. I have had them for about a month and a half but recently they have been fighting and having little skirmishes here or there. The male has a little notch taken out of this dorsal fin from it. I'm not sure what's causing this but any help would be great.

Peace River · May 25, 2019

Epicanimal said:
I have a pair of domino clowns in my 20 gallon tank. I have had them for about a month and a half but recently they have been fighting and having little skirmishes here or there. The male has a little notch taken out of this dorsal fin from it. I'm not sure what's causing this but any help would be great.

That is part of the mystery and frustration of clownfish - they truly are fantastic fish. Hierarchy and dominance is important with clownfish - it even determines who gets to grow and become the female. Skirmish are not unusual especially as the hierarchy is getting established or challenged. It is quite possible that they are in the process of bonding and considering mating which is a good thing but obviously the damage to the health of the less dominant fish can be a problem. Sometimes bonding and mating happens almost seamlessly with clown, but some level of aggression is far more common and in some cases the less dominant fish doesn't survive.

I suggest that you continue to monitor their interaction and possible actions include: make sure that there are some hiding places, moving the aquascape around so the fish have to reorient to their surroundings and instead of fighting, put the dominant fish in "time out" (e.g., a quarantine tank (QT) or the sump), and keep the water quality high so that the exposure to infection is reduced. If you move the damaged fish to QT then also move the dominant fish out of the main tank and reintroduce the less dominant fish first to reduce aggression. Good luck and let us know how it goes!

Aardvark1134 · May 25, 2019

A pair of clowns in anything less than a 55 will typically do 1 of 2 things...fight until one gives in and agrees to be the male...or fight until 1 dies. As long as you don't have 2 females the fighting should eventually end resulting in a pair.

KrisReef · May 25, 2019

Epicanimal said:
I have a pair of domino clowns in my 20 gallon tank. I have had them for about a month and a half but recently they have been fighting and having little skirmishes here or there. The male has a little notch taken out of this dorsal fin from it. I'm not sure what's causing this but any help would be great.

My wife of 30 years took a few bites out of me all day yesterday. She hasn't been feeling well and I made her dinner after a long day at my job and she complained about the soup as not having enough salt. The BBQ'd corn-on-the-cob was fantastic, but I was too tired to season the soup. I was afraid I would ruin it because I had not eaten all day and could barely see or think to cook.

This is the male's job, to take the complaints of his spouse and provide fertilization whenever she decides to make eggs. Anything else is going to cost the male domino a piece of fin. Once he learns his role she will only have to threaten him and everything will be fine if she doesn't kill him first. Se la vie.

Epicanimal · May 25, 2019

One has definitely started getting bigger.

Epicanimal · May 25, 2019

Yeah haha. They just seem to be nipping at eachother but nothing too serious and it will only last for a second or two if it is a longer fight.

Epicanimal · May 25, 2019

Yeah I will for sure try some of that out. The aquascape has some caves but I will redo it when I get my new corals In a couple of days. They were super good when I got them swimming with eachother but they were both around the same size.

Peace River · May 25, 2019

Epicanimal said:
Yeah haha. They just seem to be nipping at eachother but nothing too serious and it will only last for a second or two if it is a longer fight.

What you are describing is normal. You likely purchased two pre-adolescent fish. It is quite possible (maybe even probable) that the larger fish is evolving into a female and expressing her dominance. Good luck!