Help Overaggressive Flowerhorn

Hi! I on Saturday I got a 130 gallon aquarium with a 40 gallon sump and moved my 2 Oscars, my flowerhorn, and my blood parrot into it. Yes I am aware of the cycling and to combat that I moved everything (water, rock, decor, filter media, everything) from the 55 into the 130 and I put in water from other cycled tanks. I also am doing water tests at least once a day and and doing 15 gallon water changes 1-2 times a day. So as you can amagjne the water is a little funny right now but these are tough fish. Anyway I want to say the size of these fish. Clyde is the biggest and he is a oscar he is 10 inches long, then there is Delta he is also a Oscar and he is 7 inches long, then there captain the blood parrot who is also 7 inches long, and lastly the flower horn who is 3-4 inches long. Let me tell you one more thing, Delta has always been the type of Oscar who would rather run than fight. He almost got killed from the Blood parrot once when he went through a aggression spike. Anyway Delta has stayed that way and he will still fight sometimes but not nearly as much as a normal Oscar. Alright with all that I’m mind let me explain what happened. When the fish were moved from the 55 the pecking order reastablished and now the fish are fighting a bit. Anyway Clyde ya always been on top and he still is. Captain has always been second on top, delta has always been third and the flower horn has always been last. Anyway now I think the peckI order is becoming Clyde on top, Captain second, flowerhorn third and delta last. Let me tell you why. I just got home today to a big water mess around the 130G. It wasn’t like the tank was leaking it was like on of the fish was slashing and making a Mess I started to clean up the water and saw the flower horn chasing around delta when ever he came out in the open. Delta has always been out in the open and he has never been shy. The fact he was constantly hiding worries me especially when I saw the marks on his side and him trying to get away from the flowerhorn. The tank didn’t come with a lid so I had to costom make it so the lid has several small holes but they aren’t big enough for him to jump out of. I am worried the flowerhorn will continue to beat up delta and then maybe start to challange Captain. I don’t want the flowerhorn to be on top. I am wondering if I should let them settle it on there own of if I should put the flowerhorn in the sump for a day or two to calm him down. I will post photos and water parameters in a little bit. I’m sorry for the long pose and let me know what you think. Thanks

 

IMO I just don’t think that mix of fish are going to work. The aggression will only get worse as the Flowerhorn gets bigger. I don’t think moving the flowerhorn to the sump for a few days is going to help but maybe someone else will say different. If you are really dead set on keeping those fish in one tank your going to have to keep a close eye on them, if it gets bad which can be in a matter of minutes with these fish. Rehome or put the Flowerhorn in another tank.

 

When you got all of the fish, what order did you add them to the 55 gallon? The fish added first most likely got to the top of the pecking order and when added to the new tank it could’ve completely destroyed it and flowerhorns are extremely territorial and aggressive. The others might still be a bit shooken up after being moved to a new tank. It’s sort of hilarious to imagine a little 3” fh chasing and bullying a 10” oscar and I have a feeling that the oscar’ll put an end to things very quick. Is the tank completely bare?

 

The Flowerhorn is chasing around the 7 inch Oscar. I have a feeling the 10 inch will stay alpha for a while.

 

Typically a flowerhorn should be left by itself. If you are really wanting to make this work you might want to consider building a boarder to make sure the fish to try to be nice. Something like a light diffuser would work.

However you might need to consider rehoming the flowerhorn if it becomes to the point where it's risking the live of other mates and itself.