7 tanks? Hahaha, thats not going to fly for now. I'm going with 55g and a 30g and down the road get a 150-250g for the big predatory fish.
you can get two tanks mmm..... if i were you i would get a 400 gallon and would be a south amarican tank sting rays and angels, neons stuff from south amarica.
then a 200 gallon to play with and see if you can get a few like 5 65 gallons so when you get new fish and its sick you don't lose every thing. no gravel or plants