My first fish

Welcome to my blog. I have a 125L Fluval tank, I've had it for two years. I now have my tank as I want it, although there is always something that can be done.
My first fish that I had in my tank were black widow tetra (here's one of the suvivors), I can't honestly believe his still with us, he has had it quite rough. 
I then bought some Platties and then a couple of Mollies (I was very excited as one was pregnant) she gave birth to her fry soon after, I managed to rescue some of the fry from under the pebbles and put the in a tank nursery. Unfortunately, a few days later most of my fish were covered in whitespot. I managed to clear it up, but over the following weeks one by one, they died (of course, except one Tetra).