Platy and molly behavior

I recently rehoused 1 molly and 3 platys to a larger tank hoping it would lesson the aggression between several of them. The male platy is constantly chasing, sometimes nipping the red wag female. When the male platy is not chasing her, the black female molly is. When the male platy catches this he takes a thrashing out on the female molly (scraped sides, torn fins). Yet, everyone ignores the pregnant golden platy. She sits at the bottom of the tank by herself most of the time. She appears to have been pregnant for months. Is the aggression between platys common? Is the aggression between the female platy and female platy common? Is the aggression between the male platy and the female molly common? Is the pregnant golden's behavior normal or a pregnant platy or should I be concerned? This is all new to me.

 

Molly's and platy's are livebearers. Generally the males will harass the females if their are more males in the tank then females.

Looking at your current stock, I think some of the aggression is due to an overstocked tank. Molly's should be 1 in a 20 gallon, and platys do grow big. I think reducing the amount of your stock and separating males and females will help calm things down.

 

Oh my.........they had all been living in a 5 gallon tank and I thought the 20 would be ample. Neons and oto have not yet been rehoused to the larger tank and you say it's already overcrowded. ....sigh.....

 

Oto catfish should be in groups of 3 or more
Cory Catfish should be in groups of 4 or more

Black Molly should be in a 20 gallon or larger tank (can be aggressive)
Neon Tetras should be in a group of 6 or more
Use the 2F:1M ratio with Platies. 2 Females for every male.

There should be no ammonia and no nitrite if your tank is fully cycled.

What are you using to check your ammonia, nitrite and nitrate levels? API freshwater master kit is what is recommended here.

 

I have a Master Kit and use it to test the water in both tanks.

Had planned to get 2 more otos and 3 more neons once the small tank was available to be used as a QT. Unless I find another home for the molly, looks like that would only add fuel to the fire.

The ammonia only shows in the little tank since it was overstocked, thus water changes 2-3 times a week.

 

Again, for the record, I unwilling inherited this group of fish who had lived the last 6 months together in a 5 gallon tank. I was trying to make their lives better by moving them into a 20 gallon tank. I quick learned enough about the water quality, cycling, planting, lighting and pairing to make it this far. Only intended to purchase the 2 otos and 3 neons to fill out their minimal numbers.

 

A 20 gallon is good for your current stock. My main concern is your molly. If you could upgrade to a 29g, you'd be able to add another male and female molly and that should alleviate the aggression and you'd be fully stocked.

Otherwise, you may want to consider re-homing her.

 

From personal experience molly's can be bullies when not given enough room in the tank. I tried to keep mollies multiple times and each time they would bully my other fish. I think they are more along the lines of semi-aggressive then community.

Experience: 4 attempts with various molly breeds in 10g-55g tanks.

 

Thanks for the information folks. Things have settled considerably over the last couple of days. I am still looking into options for Ms Molly. The scraped areas on one of her side's has turned from gray to white so I think I'm going to have to move her into the 5 gallon tank and try some sort of medication. Suggestions? The white patch is not fuzzy, not raised and not sunken, she is not spotted all over, eats and is active.

 

Thanks for the information folks. Things have settled considerably over the last couple of days. I am still looking into options for Ms Molly. The scraped areas on one of her side's has turned from gray to white so I think I'm going to have to move her into the 5 gallon tank and try some sort of medication. Suggestions? The white patch is not fuzzy, not raised and not sunken, she is not spotted all over, eats and is active.

Could you post a picture of it? It sounds like a possible infection, but a picture would help us correctly diagnose it to advise you on proper treatments.