Aggressive female swordtail??

  1. ashleyb Member Member

    I have a 29 gallon tank that houses seven neon tetras, two female koi swordtails, two female red velvet swordtails, and three snails. I opted for an all female group to try to avoid breeding and aggression, although one momma did drop fry shortly after bringing her home, as to be expected I guess! I've had the kois in there for weeks without any problems and recently introduced the red velvets six days ago. Everyone was getting along great.. Until tonight.

    One of my red velvet girls is harassing the other. She doesn't bother the kois at all, she seems to have her eyes set on the other red velvet in the tank. I double and triple checked the gender of them because I initially suspected I may have gotten a sneaker male, but they are very much both female. But she keeps chasing the other red velvet around the tank and nipping at her and following her into all of her hiding spots. The tank is heavily planted with plenty of hiding areas, but she seeks the other red velvet out! I also caught her nipping at my (enormous) mystery snail but she grew bored with that quickly.

    This seems to happen in intervals. Sometimes she is absolutely fine around the other RV, but it's like she gets bored or something and starts harassing her for hours on end. I can tell it's stressing the other RV out. Could this be because she is pregnant and about to drop fry and I just can't tell? She shows no sign whatsoever of pregnancy, her stomach doesn't square off and there is no gravid spot that I saw clear as day on my previous momma. I can't even see a slight difference in coloring at all! Has anyone else had any experience with hostile females in their tanks? Should I remove her?

    Water chemistry is solid and good at 0 ammonia, 0 nitrites and 10ppm nitrates.
  2. Nicoldeme Member Member

    Fish have individual personality (As you can tell x3) So the female you have may just be aggressive by nature. If she really is showing absolutely no signs of pregnancy, I would take her out and exchange her for another, before you get too attached! Could you post a picture?

  3. chromedome52 Fishlore VIP Member

    Even virgin females will show a gravid spot, so I would consider that fish an unsexed Swordtail juvenile.

    It could become male as late as a year of age. Some Swordtail species can take a year and a half to two years to sex out, but generally helleri sex out within a year. Late males are much bigger, and are usually the breeding males in wild populations. This means they also tend to be more aggressive.

    I would also like to see a photo if possible. There are other characteristics that might give an early indication which sex it intends to become.
  4. ashleyb Member Member

    I'm sorry, it's so difficult to get a good picture of her because she hides in the plants every time I come near the tank with my phone. I'm assuming because I have a red phone case and she doesn't like it lol that sure looks like a fan shaped fin to me though??



    And also, I have four swordtails. Not a single one of them have a gravid spot, but the one who had babies sure did. It disappeared after she had her fry.

  5. ashleyb Member Member

  6. Sarah73 Fishlore VIP Member

    She doesn't look pregnant, but that's when females are most aggressive.
  7. chromedome52 Fishlore VIP Member

    Given the size of the fish relative to the heater tube, I'd say that fish is not yet mature. It could still go either way. All Swords are born with fan shaped anal fins. If it is male, then the anal fin will change shape to a gonopodium. However, the shape of the body suggests that it is more likely to go female.

    BTW, Koi Swords are notorious for having a lot of late developing males. The first time I bought them, the fish were over 3 inches, and there were two males and 5 "females". Three months later I had one female, and six males.

  8. ashleyb Member Member

    I have two of them, and I'm highly suspicious that one of them is going to be a male. He's growing at twice the rate as the other size wise, and his fin is looking more.. Pointy? As time goes by. Time will tell, lol.
  9. ashleyb Member Member

    So here we are exactly one week later.. And my koi is a male. Sigh. Hahaha. You were right! Sometime in the last week that rounded little fan fin turned into an itty bitty developing sword. It's undeniable. So much for my all female plan!!