I’m currently dealing with my tang situation.
I’ve had a purple tang for about 4 years, and I recently added a yellow tang from
@Dr. Reef.
I’m no expert and definitely don’t have a degree in fish peace-keeping, but here’s how I’m handling it and the results so far.
When fish are shipped or picked up locally, they’re already stressed. You want them somewhat de-stressed before you put them into the tank—especially before adding a fish that’s about to have a WWE Royal Rumble with the existing one for a few days, weeks, or until things go really bad.
So I placed the yellow tang into an acclimation box. I was lucky I got it from
@Dr. Reef because this yellow came tough as nails, not weak. The purple totally ignored the yellow for the first 24 hours in the box—as in, acting like the yellow didn’t even exist. After moving some rocks around, I released the yellow… and that’s when the purple tang basically told me, “HOLD MY BEER.”
That’s when I started my peace-making plan: the mirror.
First step was a complete blackout. Not just turning off the lights—I mean full garbage bags taped around the glass. It does a few important things: it lets the new tang rest and graze peacefully without getting harassed or destroyed, and it helps the purple tang get used to the yellow’s presence and scent in the tank.
The mirror was only there to take attention off the new tang. As long as the mirror was up, the purple tang would stay focused on fighting his reflection. The problem is, when he nipped at the yellow (which he did), the yellow would run away and confirm the purple’s dominance. But the mirror also kept the purple fired up nonstop, and if I removed it too soon, all that pent-up aggression would get dumped straight onto the yellow.
So for 7 days straight I used both the mirror and the blackout. I would take the garbage bags off when I was there to monitor things, and I only fed the tank while watching, ready to intervene. The tank was blacked out for about 20 hours a day (and keep in mind—I have no corals that need light). Blackout is the ultimate instant fight-stopper. Over time, the bullying went down every day, but it wasn’t sustainable long-term.
I fed the tank 5–6 times during the 4 hours I watched it. Keeping the purple tang full made him less aggressive. Another thing with the mirror: he wouldn’t eat while it was up, so I fed first,
then placed the mirror so he’d go fight his reflection, then fed again so the yellow could eat in peace.
I always read that you shouldn’t add just one tang at a time, because all the aggression gets dumped onto that one fish. Adding two can split it a bit.
I also have a hippo tang. He literally doesn’t cause any issues because the yellow isn’t a
Paracanthurus hepatus. But the purple and yellow are both
Zebrasoma, so that’s where the rivalry is.
That’s when I added a sailfin tang.
Now if you thought the purple tang hated the yellow tang, you should’ve seen him when he saw the sailfin.
He showed me what real hate looks like and instantly went to war. I didn’t use the acclimation box for the sailfin, so I did a complete blackout again, and the next morning the aggression dropped by 80%.
And since adding the sailfin, the yellow is basically on vacation—almost completely ignored by the purple. My yellow is only about 1.5 inches, so he’s no real threat to the purple. But the sailfin is bigger and faster than the yellow, and he can dodge the purple’s darts. Today (11/20/2025) in the morning, the tank was totally peaceful with zero aggression.
So here’s what I’ve learned:
The new tang should be smaller so it’s less of a threat.
Move rockwork before releasing the new one.
Keep feeding. Feeding helps a lot.
Add another tang, not just one—something like a convict tang plus another from the same family can spread the aggression.
Keep blackout ready and use it when needed and when you leave or go to sleep
Know when to use the mirror and for how long.
Redsea max S 400 tank
