i wouldn't get a snail. they infest the tank! i went through hell after getting a snail. the tank was crawling with them. but get cycle, stress coat, and salt(yes even fresh water fish benefit from salt just get the right kind. the people at the petstore will help). cycle is a brand name i'm not sure if they still have cycle per say. you need beneficial bacteria. you put it in when starting a tank and when you do water changes. sometimes it's hard to get a tank started. danios are very hardy fish. i would get those to start. i have never had good luck with guppies and neons.