Hi there. I consider myself a newbie because I've only had betta fish until now. I tried to start a tank with some harlequin rasboras, but I admit I didn't do enough research, so all except 2 of them died. So now I would like to reestablish my 10 gallon tank with some harlequins, and hopefully a few Panda Corydoras later. How many? What substrate? Any advice anyone can give me would be great. Thanks