Not sure if any of you will remember but about 2 years ago I got a bunch of Frontosa and I lost all of them bar 3. I've almost convinced myself that it's the alpha male that's been killing off the so called competition from an early age. During this last week the Alpha male has started chasing what I believe to be the dominant female since this fish and another tank mate were the only surviving Frontosa out of the bunch I got. These guys share the tank with a bunch of synodontis and smaller Malawi's and Tanganyikans there's around 25 or so fish in the tank it's 540 L in size. I've not changed the tank layout in 2 years either.

It's been suggested that he might be ready to breed and the others may not...

I'm a bit at a loss for what I should do about it, any suggestions out there? I'll try to take a picture of him and post it later for those who'd like to see him.

Pictures as promised:

The Alpha male below

And another of him:

The victim:

and another of the victim:

i have a similar situation happening but the agression is only gone so far as chasing the sub fish out of the immediate area

the tank is 2400 x 600 x 600 though

other than seperating i have no immediate solution though, sorry

edit:- mine haven't got to that stage yet, crosses fingers and touches wood

can you seperate them or put a divider in to keep them seperate

Sounds like aggression to me too

Options I would consider:

Seperate the fish.

Buy a bigger tank, most people say 6ft min for fronts they are big fish and don't tend to hide when they are getting beaten up so need the room to get away.

Add more fish of a similar size to spread the aggression out.

Remove the aggressive male as maybe he is just a grumpy bugger and get another male who might be more laid back. I have seen at least one male for sale that was sold under condition he didn't get put back with any other fronts as he just killed them off, this happens with fish at times sometimes they just have attitude problems.

Either way I would do something soon because those fish don't look too flash with those torn fins etc, if they are girls I am sure you would have no problems rehoming them to an existing colony.

What are the other fish in the tank ie the malawi's and other tangs? I noticed that when I had a single male in a mixed tank they picked on him more than he picked on them.

Could be worth re-doing the tank layout, effectively resetting all territories.

Redoing the tank wont achieve anything if these guys are smaller and less dominant he will just take as much turf s he wants.. But it might be worth a go, maybe adding a large feature breaking up the tank in the middle might help encourage him to take half the tank..

that may work as i have noticed with mine it is a visual thing, once the other guy is out of his space the agression stops

the sub fish has a flat rock angled against the side of the tank he slips into and effectively disappears

Yeah breaking up the viewing space so the dominant male can cruise around his half without seeing the others and feeling the need to smash them might help, but that would probably only help one of the others and then the less dominant maybe hit by both of them..

3 of our fronts in picture, the 7 stripe is the alpha, fish top right is the sub

I think I may have mitigated the problem. I noticed that the Male will only get aggressive when the lights are off - They'd be on from 2 hours in the morning and 4 hours in the evening. After making this observation I just left the lights on all day turning them off at night. The fish are looking a lot healthier now. For now it seems like there's a bit more peace in the tank, I'm not sure if this would be a long term solution as the algae seems to be growing a little more than before - maybe the bristle noses will have to work a bit harder.

I'll keep you posted on how this works out!

Thanks for all the advice, if this doesn't work I'll have to re-home them

Have you vent sexed the fronnies to see what sex they are?

You got some good advice from the others here on what you can do. 3 is to small a number for these guys.

Frenchy