I'm thinking about starting a peaceful community tank (which is currently cycling) and I'm wondering if diffrent schools of tetra go togeater. I wish to put them in a 40 gallon tank which has the width and depth of a normal 29 gallon but is tall. I'm thinking congo, heart tetra, black (I dont know the exact type but they have big fins), pristella, etc. Also, could I put any gourmais in there? If so what type? The gravel which I have fairly coarse and I would like a bottom dwler which wouldent get hurt. Thanks a million.