Hi All

I'm new to fish keeping, but it's something I have wanted to do for a long time and have finely got into it.
Currently, I have a 150l planted aquarium with 8 assorted male guppies, 8 Cardinal Tetra, 2 yoyo Loaches, 4 Pin Stripe Butterfly Plec and 6 Red Wag Lyretail Swordtail (3 male 3 female)

Anything, was running fine for over a month until beginning of feb.
Found 1 of the male swordtails had been beat up. I knew that the male sword tails could be aggressive to each other if they did not have females, which was why I got them in pairs (in hide sight this might be where I went wrong) he had the top of his tail nipped shorter and had a bit taken out of his lip. I kept a close eye on him that day, and he was eating and swimming around just keeping distance from the other fish so I hoped that that would be the end of it, but sadly no. Next day I found a dead fish, but not who I was expecting. it was one of the female swordtails that was dead, which was very unexpected. At this point a ran a full batch of water test and found everything was well within safe parameters and could find no explanation for why the female had died.
Moving forward, everything seamed to settle down in the aquarium until this Friday. I came in to check on everyone before I went up to bed and found that the male swordtail had been beaten up to all hell. At this point a moved him out to my 25l tank (that I had got ready 2 weeks earlier after the first incident in case there was a problem) I then saw that the dominant male swordtail was now harassing the 3rd male swordtail who had always kept a low profile (he was smaller that the other 2 male and I guess a bit younger) so I moved him out to the smaller aquarium as well.
It was this point I had my biggest surprise as saw 1 baby swordtail swimming in the tank. It is about 4 mm in size and is happy swimming about with the Cardinal Tetra and in amongst the plants.

As of today, the male swordtail that was beat up has died. I now have 1 male swordtail that all alone in a 25l aquarium. I'm worried that if I move him back he will be attacked but the dominant male and I don't want that. In the main aquarium, the baby swordtail is still alive and well, but I'm thinking that the 2 remaining female swordtails are might also be pregnant and going to pop out a load of frys.

Well, I'm not sure what I should be doing at this point and not I'm asking for Advice as I think I miscalculated the male to female ratio needed, or maybe I should never have got more than 1 male.

Thanks in advance

Matthew

For livebearers like swordtails, the minimum number of females is two to every male, and more is even better. Adding more females may take the bully's focus away from other males and onto mating with the females.