Mollies and aggression

[Kriyo87]

I just stocked my 29gal freshwater aquarium with 3 male fancy tail guppies, 2 female Dalmatian mollies and 1 male Dalmatian Molly. The tank cycled for over a month, fish-less of course, and my water parameters are as follows:

pH: 8.4 (high, I know but these were bought locally and raised in this range)
Ammonia: <0.225ppm
Nitrite: <0.25ppm
Nitrate: 0.00ppm
Temp: 72°F

I acclimated them for about an hour. All were fine. Kept them for a couple hours in low light and then gave a bit of flake before bed. Feeding was normal, no signs of aggression.

Then, I woke up this morning to find my three guppies hiding in the top corner of the tank while the Mollies took turns "herding them". It's the strangest thing. They are territorial! The 1 male Dalmation Molly is also flaring quite a bit and harassing his two female counterparts I have in there.

The females don't seem to be nipping or showing aggression to the male guppies, they just seem to be chasing them into a corner.

So, my question is will some tank mates help? Not right away of course, I don't want to overload too quickly, but I also don't want my guppies to get stressed out. Do a get a few more female mollies after a week or so? Maybe a school of tetras? Platties? Maybe add some more guppies...strength in numbers, right? Maybe not.

Also, I will be checking twice daily for ammonia. I expect a small spike over the next few days. I am using API's master test kit and I also grabbed some handy Tetra 6 in 1 strips.

If anyone has any insight into this Molly aggression, that would be awesome. I should also say that I don't have many places for them to hide, so I will add some driftwood or something and start replacing my fake plants with live ones.
Maybe that will keep them busy.

Thanks guys!

 

[BBradbury]

Your Tank

Hello Kri...

You have traces of ammonia and nitrite in the water. Even traces of these toxin are enough to stress most fish, especially Mollies that require pure water conditions all the time.

I would start a more aggressive water change routine. Ammonia and nitrites should be at "0". You can add some Hornwort or Pond weed to help steady the water chemistry. Floating plants create hiding places for the more peaceful fish and use the nitrogen from the dissolved fish wastes.

Get the water properties in order and the fish will start behaving more normally.

B

 

[wildroseofky]

Mollies can be pushy. Bad water conditions will make this worse. Even with the water straightened out there will be aggression. Mollies establish a pack order when they are put into a new territory. Males will push each other around and try to be the one to mate all the females. Male guppies will try to mate with any female. Since they are smaller than the mollies they can be killed. I lost several male guppies to a pack of male mollies. I removed all the male mollies and left three female mollies in that tank. I currently have two male guppies in that tank that I have not been able to catch and remove. The females ignore the guppies even when they try to mate with them. I have another tank with male mollies and guppies and everyone is getting along. Occasionally the males will chase each other but no one is harmed. Both tanks are heavily planted so they can hide if they need too. Female mollies will fight among themselves until one is established as the head fish. Then everyone will settle down. They may get a little pushy at feeding time because mollies are hogs.

 

[FishKitty]

Be careful. Watch your fish closely. I have a set up almost identical to yours. I started with 5 male cobra guppies and 3 mollies. They were ok at first, but when I began adding more fish the mollies started becoming very aggressive. There was one molly who seemed to be acting as the "alpha" of the three and actually ended up killing one of my guppies by fin nipping, and scared the crap out of the rest of the fish. I sat down and watched them for a while and all I saw was the mollies chasing the other fish and nipping at them. Very mean little guys. I hadn't expected that from them. After doing some more research, I learned that mollies can be difficult to keep because of their territorial behavior. They need very pure water conditions and you have to be very careful about what tank mates you choose to put with them.

Of course, BBradbury and wildroseofky are absolutely correct when they say that bad water conditions make this worse. I would say DON'T add any more fish, especially until you get your water conditions in better shape. Adding more fish will just increase your ammonia levels and increase the territorial behavior. The good bacteria hasn't grown enough to catch up with the waste in the tank yet. That's the downside of trying to start from scratch and do a fishless cycle - there's no fish waste, so the good bacteria can't really grow.

I ended up removing my mollies from my tank. Since I removed them, the other fish seem much more calm and everyone appears healthier. My water conditions have also improved because there is less waste. You probably don't want to have to remove any of your fish, and you may not have the necessary equipment for that to even be an option. I would just say try to take it slow and be patient. Tanks can take months before they are finally well established.

If you don't already have one, try using a sponge filter or prefilter sponges (which hook up to your power filter's intake). Sponges are much better for collecting the good bacteria. The filter inserts that hold carbon do this too, but because of the high flow rate and the need for frequent replacement, it can be hard to maintain. Remember, its not the water that has to cycle, its the whole tank. Its your plants, your substrate, everything. It all needs to develop a good population of bacteria.

Good luck!

 

[seove]

Too many males. You should have 2-3 females for each male.