My Angel Fish has suddenly become aggressive to one of my Mollies.

bigdogtech

Member
As the Title says in my 20 gallon fresh water Tropical tank, my one angel wish has suddenly became aggressive to one of my larger Male Mollie, all the tank peramaters are normal 0 Amonia - 0 Nitrite - 40-60 Nitrate, and my last water/gravel cleaning was on the 15th. The only thing I found online about this is that I should change the water less often due to territorial pheremones the Angel produces through it's urine. This has not happened at all while keeping this Tank, and the angel was still young when I introduced the mollies. I really don't want to separate this Mollie but if there is no other solution I might have to. Please help
 

Spudsssy

Member
Simply comes down to territory. Over time once cichlids mature and become settled in the tank they can show aggression. Angel fish need at least 40-50 gallons+ if kept with other fish. There simply isn't enough territory for it not to show aggression in a 20gal. Granted every fish is different and male/female makes a big difference too, but I don't think there is anything you can do in a 20gal to solve aggression issues.

Moving tank decor around and trying to block line of sight often help but long term i don't think this will solve the issue.

I don't like any form of harassment or aggression, so I always double/triple recommended tank size for territorial fish as recommendations online are generally bare minimums.
 
  • Thread Starter

bigdogtech

Member
Spudsssy said:
Simply comes down to territory. Over time once cichlids mature and become settled in the tank they can show aggression. Angel fish need at least 40-50 gallons+ if kept with other fish. There simply isn't enough territory for it not to show aggression in a 20gal. Granted every fish is different and male/female makes a big difference too, but I don't think there is anything you can do in a 20gal to solve aggression issues.

Moving tank decor around and trying to block line of sight often help but long term i don't think this will solve the issue.

I don't like any form of harassment or aggression, so I always double/triple recommended tank size for territorial fish as recommendations online are generally bare minimums.
I don't know how to tell Gender with Angel fish, but another thing with my angel is that it has never been aggressive before now, It only goes after the one though if it gets to close, all the others ones can swim around it freely and no aggression is shown.
 

Spudsssy

Member
How big is the angel fish? They can get pretty big at 6 inches. If you bought the angel fish as a juvenile you wouldn't see much aggression. Problems start when they mature.

It is pretty common for territorial fish to focus on a particular fish. If you remove molly it doesn't guarantee it won't pick on a different fish I'm afraid.
 
  • Thread Starter

bigdogtech

Member
Spudsssy said:
How big is the angel fish? They can get pretty big at 6 inches. If you bought the angel fish as a juvenile you wouldn't see much aggression. Problems start when they mature.

It is pretty common for territorial fish to focus on a particular fish. If you remove molly it doesn't guarantee it won't pick on a different fish I'm afraid.
My Angles body seems less than 6 Inches but total length with fins is probably more around 6, And this is the Troublesome Mollie
 

Spudsssy

Member
Try to break up the tank with plants and ornaments, so the angel fish can't always see the molly. This makes a huge difference.
 
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bigdogtech

Member
Thanks for the Help Spudsssy. Sadly My decor can't really be re arranged to do that.
 

Nikn

Member
It's definitely a territory thing. I would suggest rehoming the angel otherwise he might kill the molies. Also mollies and angels have different water requirements, angels need softer water and mollies need harder water. I guess you could try to break their line of sight but I'm not sure if it will work in the future. You should consider getting another tank for either your angel and the mollies.
 
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