I did a 50 gallon cray fish breeding tank I got lots of PVC from Home Depot and got different sizes from 1/2 inch to 1 inch stacked em in like 3 walls with no substrate no plants i made like cray fish condos it worked for a while but got rid of my puffer so got rid of my crayfish if your looking to keep em as a pet fake plants are the way to go they will eat and tear up any real plants