How do you deal with changes in aggression?

reely989 · 2026-09-10T10:20:55-0400

So I'm past the 2 year mark on my 300 gallon tank and it's pretty well established and stocked at this point. What I'm running into now over time are changes in who thinks they are the boss of the tank. For a long time it's been my king angel and while he's been a pain to some other fish he doesn't really do much other than chase. The last few weeks though it seems like my sailfin tang has realized he's actually bigger and badder than the angelfish and has kind of asserted himself as the head honcho in the tank. He's a little less nice than the angelfish and is absolutely terrorizing my foxface. He's camouflaged and spiked up just about all the time now. I'm gonna add some rocks and keep up some mirrors for a bit to see if it helps. Any other tricks you guys have had work for situations like this?

Fish Fan · 2026-09-10T10:30:02-0400

@vetteguy53081 may have some suggestions here if he has a minute to check in

mfinn · 2026-09-10T10:38:55-0400

I'm going through the same thing with tangs in my tank.
I recently lost the hippo tang who was the tank boss and kept my 3 yellow tangs in line.
Now that the hippo is gone, 2 of the yellow tangs have been going at it.
I am doing the mirror trick and have a little success.

winxp_man · 2026-09-10T10:45:31-0400

Feed more times and day can help. I feed less at one setting but more times during the day.

Nori, ogo, mysis, black worms, spectrum pellets, easy reef dki pellets.

vetteguy53081 · 2026-09-10T10:52:13-0400

Fish Fan said:
@vetteguy53081 may have some suggestions here if he has a minute to check in

Isolation in a separate tank or with divider. I currently have 2 fish in a sump for a 3 month timeout

reely989 · 2026-09-10T10:55:18-0400

winxp_man said:
Feed more times and day can help. I feed less at one setting but more times during the day.

Nori, ogo, mysis, black worms, spectrum pellets, easy reef dki pellets.

Think I'm gonna do this, too. I do notice that aggression tends to go down with increased feedings and my fish are all pigs so none of it ever goes to waste.

winxp_man · 2026-09-10T11:21:51-0400

reely989 said:
Think I'm gonna do this, too. I do notice that aggression tends to go down with increased feedings and my fish are all pigs so none of it ever goes to waste.

One day I decided to keep them off some food to get them to pass what they pig out on. Biggest mistake ever. I had 15 ticked off tangs wanting to kill each other in a real bad way. It didn’t help that the next day I was stuck out of town and couldn’t get food. So two days everything went ballistic. Even the angles went after each other. Never again. So I feed less but more times a day.

BryanM · 2026-09-10T12:12:31-0400

reely989 said:
Think I'm gonna do this, too. I do notice that aggression tends to go down with increased feedings and my fish are all pigs so none of it ever goes to waste.

How often do you feed today?

I got an auto feeder and started feeding 3x a day, when I did that I saw most aggression die down. Now the sailfin chases or pushes some, but its very brief.

reely989 · 2026-09-10T12:18:54-0400

BryanM said:
How often do you feed today?

I got an auto feeder and started feeding 3x a day, when I did that I saw most aggression die down. Now the sailfin chases or pushes some, but its very brief.

Oh man, probably ever couple of hours at least on the planks I have and then a couple of other supplemental feedings with a frozen feeder. They probably get 6 or 7 helpings of food a day.

BryanM · 2026-09-10T12:20:08-0400

reely989 said:
Oh man, probably ever couple of hours at least on the planks I have and then a couple of other supplemental feedings with a frozen feeder. They probably get 6 or 7 helpings of food a day.

Ah, that sounds like plenty. Maybe a timeout like vetteguy said is in order.

reely989 · 2026-09-10T12:21:29-0400

BryanM said:
Ah, that sounds like plenty. Maybe a timeout like vetteguy said is in order.

What's annoying is the sailfin's colors and fins look so good when he's all riled up and being an butt haha. But the other fish don't like him very much at the moment.

BryanM · 2026-09-10T12:54:51-0400

reely989 said:
What's annoying is the sailfin's colors and fins look so good when he's all riled up and being an butt haha. But the other fish don't like him very much at the moment.

I can't believe how big they get when they "puff up". Its at least another 1/3rd bigger.

exnisstech · 2026-09-10T13:28:49-0400

I have 9 tangs a few 5,9, and 10 years and they definitely change as they get older. I've been noticing a big increase in activity when lights start to dim and the little fish go into hiding. My convict becomes a true butthead during that time but I've started tossing some pellets in and it seems to be belongs. My yellow tangs get aome grief from the others during the day but there's 4 of them and none get singled out and i don't see any fin damage, just short chases.

reely989 · 2026-09-10T13:39:29-0400

BryanM said:
I can't believe how big they get when they "puff up". Its at least another 1/3rd bigger.

It's pretty amazing. Mine's grey color also darkens almost to a total black. It looks so good against his yellow stripes. Unfortunately when he looks like that I know he's just being a turd.

winxp_man · 2026-09-10T16:29:17-0400

exnisstech said:
I have 9 tangs a few 5,9, and 10 years and they definitely change as they get older. I've been noticing a big increase in activity when lights start to dim and the little fish go into hiding. My convict becomes a true butthead during that time but I've started tossing some pellets in and it seems to be belongs. My yellow tangs get aome grief from the others during the day but there's 4 of them and none get singled out and i don't see any fin damage, just short chases.

It’s almost as if you need to get the light off right away not much dimming. These fish do go nuts with moon light. I have ration xr15’s pros and left the moon light on. Boy o boy! I stopped that real quick! Never again. I will soon be doing more rock work in my system. Never can have enough. They love the caves.

exnisstech · 2026-09-10T16:39:39-0400

winxp_man said:
It’s almost as if you need to get the light off right away not much dimming. These fish do go nuts with moon light. I have ration xr15’s pros and left the moon light on. Boy o boy! I stopped that real quick! Never again. I will soon be doing more rock work in my system. Never can have enough. They love the caves.

Agreed. Problem I have is the tank is in our living room adjacent to a big TV ans my Gal stays up late watching movies. I thought about looking into a some type of portable shade but being a 7ft tank I'm not sure what i could use that would be easy to store during the day. My gang is up as soon as daylight enters the windows and the lights don't come on till 5 hrs later.