hi! I work in a pet shop and you'd be surprised how many people don't even bother asking so...Well done! A good size tank would be about 15litres (seems a bit excessive I know but gives them plenty space),minimum would be around 10litres. They will also need a filter and a heater. The heater should be set to around 24/25 degrees. You'll have to do a 20% partial water change every week as well but remember to dechlorinate the fresh water and let it come to room temperature before you put it into the tank. Think thats the basics but if you have any further questions just ask! oh yeah! don't put it in beside other male fighters or fin-nippers like barbs and don't forget to feed it to keep it happy and it might even make a bubble nest for you!!