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Aggressive Male Molly Attacking New Female


Jan 5, 2012
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Oakville, Ontario Canada
Hello, I'm hoping some of you may have some thoughts around some behaviour I'm seeing in my tank.

Some background - The tank is well estabished 90 Gallon which is heavily planted I have a mature angelfish pair, some cory and oto catfish with a few mollies. Regarding the mollies: For quite some time i have had a male (silver high fin) in with two females (a gold and a Dalmatian) which he gets along fine with and mates regularly with both. Last week I decided to add a female silver molly of similar size to the mix after a period of quaratine . I assumed he would be delighted and it would spread his mating attention around a bit better and give me a 3:1 ratio.

Apparently he hates the new female as from the moment he saw the new female he aggressively attacks her (this is not mating...I know what that looks like). In between attacking her he continues to mate with his other females. I assumed this would resolve itself and he would calm down shortly. This morning I see she has rips on her dorsal fins and I removed her to my quarantine tank to heal. At this point I have the following thoughts: He simply dislikes the new fish? Could the similar coloration to his own be a factor? Otherwise I'm baffled as I expected he would be thrilled to see another female.

Thank you in advance for your thoughts