Mirror Trick Worked Too Well

[Robert M]

So I decided to add a powder blue tang to my tank with an established sailfin tang and emperor angel (and some smaller fish). Being a bit paranoid about fish fighting I put the PBT in an acclimation box and tried out the “mirror trick”. I stuck a small shower mirror against the side of my tank to distract my established fish when I released the PBT. Immediately my peaceful sailfin started going nuts battling the mirror. I turned off the lights and after a bit went to bed.

Early this morning my son grabbed a pre-dawn picture of the epic battle.

When I got up I took the glass mirror out and was stunned to see the tang had nearly destroyed the glass. In just 12 hours, the sailfin had put dozens of scratches in my mirror. I had no idea an angry fish could scratch glass!

Anyway, mirror is out and no one seems to mind the new PBT. Now I just need to be careful that I never anger my sailfin else it might scratch up my aquarium!

 

[jah-hoeva]

Why did you put the mirror inside the tank? I thought typically people put them on the outside of the glass.

 

[Robert M]

Well after this experiment, putting the mirror on the inside seems like the correct approach—otherwise my tank glass would have been scratched! Mounting on the outside seems like a bad idea unless you only have a mirror with a metal rim that shouldn’t be in salt water and you don’t mind your fish scuffing your tank.

Plus, I got a waterproof, suction-mounted mirror that is meant to be mounted on the inside.

 

[Phinfan]

Usually outside the tank pretty sure the aquarium glass would hold up better then the mirror

 

[dz6t]

Last time I put a mirror on the tank, like more than 10 years ago, many fish were looking at themselves in the mirror, like kids in an amusement park.

 

[Matt L.]

I’ve always placed the mirror outside the tank. I have never had great luck with using the mirror trick, especially with highly aggressive fish like PBTs. I’d recommend using a piece of eggcrate to divide the tank, keeping the PBT on one side and the existing tangs on the other. Then after a few weeks remove the eggcrate but be careful.

Matt

 

[1spotpooalot]

I just did this trick for the first time whille adding a smaller desjardini to my tank with an established and bigger Scopas. The sailfin is staying next to the mirror like it is looking for help from a buddy...while the jerk Scopas charges the glass....but it seems to work a little. I think the Scopas thinks there are 3 new fish and is less likely to charge the 1 real new one. He thinks I added 2 sailfins and 1 scopas; Mean fish but not the brightest bulb on the tree. Lets see if it works long term

 

[1spotpooalot]

Update....the mirror trick works!. If I take the mirror away, I have a fight on my hand. While in place, the scopas doesn't go after the desjardini. I swear he thinks there are multiple fish in the corner and the desjardini will cuddle up to his reflection. Hes starting to wander out and aggression has lessened