So, I set up a 20 litre aquarium about a month ago. I have already have a filter and a heater. After cycling the tank for about a week, I bought a female platy and added to my tank. At the same time, I was given a four month old male platy from my neighbour, and added that to the tank as well. They both seem to be doing fine. It's been a month now, and I today, I went and bought two guppies (one male one female) and two neon tetras. I floated them for 15 minutes and added them to my tank. I know that i should have a couple of females for each male guppy, but I did not want to overcrowd the tank. They all the seem to be doing great, however, every time I walk past the tank, I see the female guppy constantly chasing away and nipping at the male guppy. I don't know what to do, if I buy one more female guppy, i may overstock the tank.