A Little Darkness can HELP: How i stopped my angelfish from being bullied
In my 210-gallon planted tank, I keep four beautiful angelfish. The tank is full of lush plants and hiding spots, and for the most part, the fish coexist peacefully. But back in April, I noticed something was off: one of the four angelfish started getting picked on.
He wasn’t injured yet, but the tension was obvious. He kept his distance, wasn’t eating as much, his tail fin was clearly being nipped, and the fish was clearly stressed. I had to make a quick decision — I was going out of town for a few days and didn’t want to come home to a sick or injured fish.
Note the torn tail fin on the angelfish on the bottom right.
There are a few classic solutions to aggression in angelfish:
Add more hiding spots – My tank already had plenty.
Separate the bullied fish – Not ideal with me being away.
Rehome a bully – A bit drastic and not something I wanted to rush.
Add more angelfish – Sometimes changes the dynamic, but risky without time to monitor.
Reduce lighting – A gentler, lower-stress approach.
With time running out and stress rising in the tank, I decided to turn off the aquarium lights for the full 4 days I was away.
When I returned? The bullied angelfish was calm, active, and eating again. There tail fin was looking better, no other signs of trauma, and the plants — despite the lack of light — were totally fine.
Fast forward to now, in June: That same angelfish still tends to hang slightly apart from the other three, but he’s healthy, always eating, and showing no signs of aggression from the group.
What I Learned:
Lighting impacts behavior. Just like people, fish can become overstimulated.
Aggression isn’t always permanent. With space and time, social hierarchies can shift.
You don’t always need to intervene aggressively. Sometimes, gentle environmental tweaks can be just as effective as rearranging the entire tank.
Every tank is different — what worked for me might not work in every situation. But if you’re dealing with mild aggression and don’t want to immediately isolate or rehome a fish, a lighting break might be the low-stress solution you didn’t know you needed.
Have you dealt with bullying in your tank? Share your experience in the comments — or let me know if you’ve ever tried dimming the lights to shift the mood in your aquarium.